Rain barrel math

[frugalnacho]

I looked into making a rain barrel a few years ago when it was all the rage, and the math just didn't add up, and the payback period was 20-30+ years.  It's still all the rage, so I ran the calculations again, and it still doesn't make sense. 

I pay about $8.60 per 1 unit of water, which is 100 cubic feet, which is 748 gallons.  Approximately 1.1 cents per gallon.  A typical rain barrel holds 55 gallons, or about 60 cents worth of water.  Even if I can snag a barrel for free, the cost of the accessories to hook it up to my gutter system will take my lifetime to pay back at only 60 cents saved per barrel.

I don't water my lawn at all, but I do water my vegetable/fruit garden and based on my bills I am using about 3,000 gallons/month so far this year, or about $30-35/mo in water.  A 55 gallon rain barrel will not even put a noticeable dent in that, especially considering I will not be using it during rainy days, and only using it during non rainy days.   I think a drip irrigation system will cut my water usage in half by using it much more efficiently, but one barrel only gives me a couple days worth of water during hot/dry parts of the summer. 

The footprint of my house is 24'x24', which should give me about 359 gallons per inch of rain.  Nearly all of that will go to waste with a small barrel.  If I get some much larger IBC totes (275 gallons) I can actually catch most of the rain water.  My area typically averages a little over 3 inches per month from April-September.  That gives me about 1,100 gallons of water each month coming off my roof, on average.  2 IBC totes would give me 550 gallons of capacity, which should be enough to catch nearly all the rain, and water my garden.  I may still have to supplement with hose water, but I should be able to catch and utilize most of the rain during the growing the season. 

The cost of food grade IBC totes around me seems to be around $100/ea, plus I would have to go pick them up with a truck.  I would then have to buy PVC to hook everything up to my gutter system.  I'm thinking i'll need another $100 worth of stuff to get it all hooked up, putting me around $300 for the entire set up (not including the actual drip irrigation, which I'm probably going to set up regardless of the rain barrel situation so I'm not including that).  All to catch and use the approximately $70-75/yr worth of rain falling on my roof.

Based on these numbers I'm looking at between 4 and 5 years pay back for setting up a 2 tote 550 gallon system.  Of course this doesn't include any maintenance or anything, and I'm assuming this system will be like every other project I've done and not be completely cost (and headache) free during that time period.  Plus I will permanently lose a footprint of about 4'x8' in my yard to store these containers year round.

One part of me hates seeing all that free rain water go down the storm drain while I am paying to run my hose.  Another more practical part of me thinks I will be better off financially if I simply focus all that energy I would otherwise spend on setting this system up by just doing something else to save/make money.



Does anyone here have or use a rain barrel system?  Was it a financial decision, or just a green decision (even if it doesn't save you money)?

Is it worth it to set it up with that payback period?  Are there any hidden or recurring costs which I have neglected to include above?  Is there anything else wrong with my math?

[Prairie Stash]

I purchased a rain barrel via a city program that broke after a year :( DIY is much better. I whipped up a spreadsheet at the time, it has a picture of the broken barrel.

I currently run 2-200L barrels in series, if you're using a tote why not start with one and expand if needed?  The simple connection is to raise them and have the overflow cascade from one to the next. A better system is to create a manifold at the outlets and have them fill from the bottom up (parts are more expensive). I have them along my fence in a part of the yard that was useless, taking care of the annoying space problem. Also you need to raise barrels, they work better as in you get more water pressure on your hose the higher you raise them. I used some cindercrete blocks I got for free, my full barrels weigh 450lbs each (210L water is heavy).

Rain water is softer and warmer than city water,its generally easier on younger plants, so it marginally improves their growth. Its easier on city infrastructure, my city treats storm runoff, but that's not your problem (that's why my city was promoting barrels). For maintenance I'm a few years in and I need to clean the screens (screens prevent mosquitos from laying eggs)every year, shingle rocks collect on the screen, but otherwise I don't do anything. Eventually I'll clean out the barrels but the exit spout is 2 inches from the bottom so It will take a while for dirt to accumulate enough to matter. I've forgotten water over the winter a few times and its frozen, no big deal with good plastic barrels.

If you have a 4-5 year payback then its worth it. It will take a few hours to set up and its a fun project. Its worth more than composting, do the math on soil sometime, with less effort (I compost too, don't attack me as an anti-compost commie or whatever).

[BlueMR2]

For it to make sense for me, they'd have to give me the rain barrel for free.

Perhaps that will happen someday...  We do have yard watering limitations sometimes in the Summer, so there's incentive to get people other methods (doesn't affect me though, I have my own well for watering the lawn).

[Glenstache]

Food grade barrels show up on craigslist pretty regularly. The only additions will be a spigot at the bottom and hole and screen at the top. Our outdoor water usage is so minimal that it has never made sense, though I may consider a rain garden at some point to mitigate runoff from the gutters.

[Slee_stack]

There was a program at REI once upon a time.  For $20 or so, we each got a short class (history, propaganda, whatever), a barrel, and a kit to connect it to a downspout.

Not sure we ever saved any money, but the cost was pretty low overall.  We do 'shotgun' our garden (use both barrels).

Curiosity and some level of ECO consciousness were drivers, not cost savings.

[frugalnacho]

I purchased a rain barrel via a city program that broke after a year :( DIY is much better. I whipped up a spreadsheet at the time, it has a picture of the broken barrel.

I currently run 2-200L barrels in series, if you're using a tote why not start with one and expand if needed?  The simple connection is to raise them and have the overflow cascade from one to the next. A better system is to create a manifold at the outlets and have them fill from the bottom up (parts are more expensive). I have them along my fence in a part of the yard that was useless, taking care of the annoying space problem. Also you need to raise barrels, they work better as in you get more water pressure on your hose the higher you raise them. I used some cindercrete blocks I got for free, my full barrels weigh 450lbs each (210L water is heavy).

Rain water is softer and warmer than city water,its generally easier on younger plants, so it marginally improves their growth. Its easier on city infrastructure, my city treats storm runoff, but that's not your problem (that's why my city was promoting barrels). For maintenance I'm a few years in and I need to clean the screens (screens prevent mosquitos from laying eggs)every year, shingle rocks collect on the screen, but otherwise I don't do anything. Eventually I'll clean out the barrels but the exit spout is 2 inches from the bottom so It will take a while for dirt to accumulate enough to matter. I've forgotten water over the winter a few times and its frozen, no big deal with good plastic barrels.

If you have a 4-5 year payback then its worth it. It will take a few hours to set up and its a fun project. Its worth more than composting, do the math on soil sometime, with less effort (I compost too, don't attack me as an anti-compost commie or whatever).

Why 2 totes? I think I might need the capacity of 2 totes.  Currently using 3,000 gal/mo, but I think a more efficient drip irrigation will use half that, so 1,500 gal/mo or 50 gal/day.  One tote (275 gal) will only give me about 5 days worth of watering, so if I encounter a heavy rain I will not only not need to water the garden during that week, but I'll collect a disproportionate amount of my expected monthly average of rain (1,100 gal/mo).  With only 275 gallons, most of that heavy rain will run off and go to waste.  I'll have to replace all that run off (and them some) with my hose to meet my water demands.  Maybe some of my estimates are off here (hopefully everyone can check my math and assumptions), but I think the second tote will have a much better ROI than the first.  The additional $120-150 for a second tote and the bulk heads required to increase the system capacity hopefully will be earned back very quickly, and then help the entire system to an earlier break even point as compared to a single tote system.  Plus I am going to have to borrow a pick up truck and travel out to the locations that have totes available for purchase.  If I wait to add the second tote I'll have to borrow the truck and go buy another one again.

I can also use wasted space in my yard for the totes, though I am concerned it will be an eyesore.  All things being equal I would rather have fewer object on my property, but if it provides a benefit I can deal with it.  My highest beds are 2 cinder blocks high (15.5"), so I will have to elevate the totes above that.  I was thinking about 4 cinder blocks high (31"), that would give me a minimum of 15.5" when the tote is almost empty, more when it's fuller.  Also the yard slopes down toward the garden so that will provide additional elevation.  I still have to measure the elevation change from house to garden, I think it's positive but small.

I have a DIY compost barrel I use. I also have worm tubes (or worm cafes, or worm hotels).  Basically a worm tube is a 4" PVC pipe, about 2.5' long with 2' buried in the ground.  6 sets of 4 holes (24 holes total) all at 90* angles from each other (holes are about 5/8") are drilled along the submerged portion of the tube and a cap is set light on the top of the tube.  Organic matter is placed inside the tube and the cap is put back on.  Worms come in and eat the organic matter, then crawl back out to the dirt and leave their castings.  We installed the tubes this year and have been using them for about 2 months.  It's like a bottomless organic garbage can.  They get full quickly if we generate a lot of trash (a large watermelon rind will completely fill the tube and then some), but the worms seem to eat fast.  I only have 4 installed now, and we have run into a situation where they were at 100% capacity once after a party (with the aforementioned watermelon), so I think I am going to buy another 10 foot tube and install 8 next year.  I probably won't need to use the compost barrel at all with 8 tubes.  My city does composting and I can get unlimited free compost at the beginning of the season through them so it won't save me any money, but it's still more efficient to just to it directly.  My motivation for composting was environmental not financial, plus it's a neat project.  My niece loves filling the worm tubes with vegetable scraps. 

[Glenstache]

I have a DIY compost barrel I use. I also have worm tubes (or worm cafes, or worm hotels).  Basically a worm tube is a 4" PVC pipe, about 2.5' long with 2' buried in the ground.  6 sets of 4 holes (24 holes total) all at 90* angles from each other (holes are about 5/8") are drilled along the submerged portion of the tube and a cap is set light on the top of the tube.  Organic matter is placed inside the tube and the cap is put back on.  Worms come in and eat the organic matter, then crawl back out to the dirt and leave their castings.  We installed the tubes this year and have been using them for about 2 months.  It's like a bottomless organic garbage can.  They get full quickly if we generate a lot of trash (a large watermelon rind will completely fill the tube and then some), but the worms seem to eat fast.  I only have 4 installed now, and we have run into a situation where they were at 100% capacity once after a party (with the aforementioned watermelon), so I think I am going to buy another 10 foot tube and install 8 next year.  I probably won't need to use the compost barrel at all with 8 tubes.  My city does composting and I can get unlimited free compost at the beginning of the season through them so it won't save me any money, but it's still more efficient to just to it directly.  My motivation for composting was environmental not financial, plus it's a neat project.  My niece loves filling the worm tubes with vegetable scraps.

I'm really intrigued by this. Is your implementation about the same as the link below?
http://garden.org/regional/report/arch/inmygarden/3430

[frugalnacho]

Food grade barrels show up on craigslist pretty regularly. The only additions will be a spigot at the bottom and hole and screen at the top. Our outdoor water usage is so minimal that it has never made sense, though I may consider a rain garden at some point to mitigate runoff from the gutters.

I have some barrels, it still doesn't make financial sense to get the hardware required to hook them up.  I think anything less than 3 barrels would probably be useless to me and would never pay itself off.  Wouldn't even be worth the hassle either to only displace like 5% of the watering needs.  I only have $70-75 worth of rain fall on my roof during the growing season, and the smaller my containment system the less of that potential $75 I can retain.

[frugalnacho]

I have a DIY compost barrel I use. I also have worm tubes (or worm cafes, or worm hotels).  Basically a worm tube is a 4" PVC pipe, about 2.5' long with 2' buried in the ground.  6 sets of 4 holes (24 holes total) all at 90* angles from each other (holes are about 5/8") are drilled along the submerged portion of the tube and a cap is set light on the top of the tube.  Organic matter is placed inside the tube and the cap is put back on.  Worms come in and eat the organic matter, then crawl back out to the dirt and leave their castings.  We installed the tubes this year and have been using them for about 2 months.  It's like a bottomless organic garbage can.  They get full quickly if we generate a lot of trash (a large watermelon rind will completely fill the tube and then some), but the worms seem to eat fast.  I only have 4 installed now, and we have run into a situation where they were at 100% capacity once after a party (with the aforementioned watermelon), so I think I am going to buy another 10 foot tube and install 8 next year.  I probably won't need to use the compost barrel at all with 8 tubes.  My city does composting and I can get unlimited free compost at the beginning of the season through them so it won't save me any money, but it's still more efficient to just to it directly.  My motivation for composting was environmental not financial, plus it's a neat project.  My niece loves filling the worm tubes with vegetable scraps.

I'm really intrigued by this. Is your implementation about the same as the link below?
http://garden.org/regional/report/arch/inmygarden/3430

Pretty much.  I purchased a 10 foot 4" diameter pvc drain pipe (I think) at home depot.  It was like $15-20 including the 4 caps. 

Can't comment on the long term success since I've only been using them for 2 months, but all that organic material is going somewhere.  The garden is growing like gangbusters too, but I don't know how much the tubes are contributing to that.

[Capsu78]

I have a well so my 2 80 gallon rain barrels are just my go to water for pots close by.  When water is tight and the well level is down, it feels like a luxury when even a quick storm tops them off.
I will offer that my 3 cats- 1 deceased, 1 9 YO and a new addition have all "found" the watering cans next to the barrels as of "fine vintage", so if a cat gets stuck outdoors, they prefer that water to the fountain.   

I also use the rain barrel water to feed and if rain is coming and I have water to spare, I sometimes do a bonus watering. 

BTW, my barrels are recycled olive barrels from Greece- perhaps the last good to still be shipped out of Greece! 

[Prairie Stash]

Why 2 totes? I think I might need the capacity of 2 totes.  Currently using 3,000 gal/mo, but I think a more efficient drip irrigation will use half that, so 1,500 gal/mo or 50 gal/day.  One tote (275 gal) will only give me about 5 days worth of watering, so if I encounter a heavy rain I will not only not need to water the garden during that week, but I'll collect a disproportionate amount of my expected monthly average of rain (1,100 gal/mo).  With only 275 gallons, most of that heavy rain will run off and go to waste.  I'll have to replace all that run off (and them some) with my hose to meet my water demands.  Maybe some of my estimates are off here (hopefully everyone can check my math and assumptions), but I think the second tote will have a much better ROI than the first.  The additional $120-150 for a second tote and the bulk heads required to increase the system capacity hopefully will be earned back very quickly, and then help the entire system to an earlier break even point as compared to a single tote system.  Plus I am going to have to borrow a pick up truck and travel out to the locations that have totes available for purchase.  If I wait to add the second tote I'll have to borrow the truck and go buy another one again.

It sounds well thought out. Doing a ROI on the second tote is hard. You have to assume the first tote is overflowing and filling the second tote with each rain. As you know rain isn't evenly spaced nor is the same amount each time. Some people get 0.5 inches a week, which you would need one tote for, and some get 3 inches in a week followed by 3 weeks of dry (you would need 4 totes to capture). I tend to get rain clusters followed by several weeks of dry in my area. During the rain clusters I store and during the dry I drain my tanks first then switch to city water.

I probably get a better ROI from the first barrel based on utilization than the second, I think its fair that all extra costs are attributed to the first as well. Often I still have water in the second when it rains and tops up my primary. Overall its splitting hairs though, one might have a payback of 4 years and the other 6, both are great deals. For all I know you might want to expand to 3 totes in a few years, its up to you. 

I use to have a worm bin for composting, it was fun, now I've switched to the simple barrel system. I ended up slightly up on everything by selling worm kits online, I could sell a kit every 3 months and net $20 which isn't going to make me rich but was a time saving trick. If you get a good design for rain water you can also sell those as a side project. Keep track of your costs and usage, its an easy way to make a few dollars and feel good about helping the environment. One day I'll teach my kids how to do all of these small money makers, its the modern version of lemonade stands.

[rockeTree]

My veggie garden likes rainwater much much more than city water (we did a science fair project on it one year and the radishes at least are a slam dunk!) so it's worth it for me for the ecological warm and fuzzies (we're very near a stream) and the happier plants. We have higher rates though, too, I think my breakeven on the hundred gallon barrel was maybe 6-7 years. You're not gonna get rich or bankrupt yourself either way, and it's likely not a recurring purchase, so do what you want to do and feel ok about it :-)

[HAPPYINAZ]

We have a totally free system since my husband found the the 55 gallon plastic barrels.  He even found a lid that fit one recently.  We just put our downspout into one of the barrels so the run off flows into the barrel and overflow just spills out onto the ground where the spout used to spill.  The other two barrels (plus some plastic rubbermaid tubs we also found) sit underneath a section of roof that has no gutter.  The rain normally just poured off and now it pours off into the barrels.  All the barrels and tubs fill with very little rain.  I use a found plastic bucket to haul the water to the plants (yea! exercise!).  I did buy some of those packets of mosquito floats....forgot exact name of them...they are donut shaped things that float in the water and kill mosquito larvae but are not toxic to much of anything else.  Only need a portion of a donut for each barrel.  If we had tighter lids we probably wouldn't need those.  our system doesn't completely replace our watering needs, but it makes me feel better not using potable water on the plants.  But it was free and took just about zero effort to install.  You don't need complicated hardware to collect rain water. 

[deborah]

Why not a rain water garden? See http://www.melbournewater.com.au/raingardens

[A440]

My dad used some discarded water heaters.  I assume they probably did have some scrap value, so you might have to pay something for them.  Can be more cost effective.  May not be the most cosmetically appealing.

[tardis]

Also look into DIY wine places for used plastic barrels.  We got one for about $20 or $30 about 10 years ago and it's done just fine through multiple Canadian winters and with full exposure.  We mounted it on it's side at porch level and were then even were able to stick a proper tap in it to fill watering cans and so forth.

[alsoknownasDean]

Are you in an area prone to drought?

If the local reservoirs are running low (low enough for water restrictions), having access to an additional source of (admittedly non-potable) water is a good idea.

My parents have a huge 22500L tank at their place (although they also have town water). It'll be useful when we have our next drought. I've even made beer with the tank water.

[frugalnacho]

Why not a rain garden? Most of the garden beds are already built and I don't feel like redoing them.  The new ones I build are going to be in the garden area which is no where near my house.  I will probably need to run a 75 foot garden hose from my rain totes next to my house into the garden to water them.  It would probably be easier and cheaper to just implement a 550 gallon rain barrel system than it would to redo the beds and plumb them up to be rain gardens.  I imagine I would have better overall control of the water with an irrigation system as opposed to a rain garden too.

Are you in an area prone to drought?

If the local reservoirs are running low (low enough for water restrictions), having access to an additional source of (admittedly non-potable) water is a good idea.

My parents have a huge 22500L tank at their place (although they also have town water). It'll be useful when we have our next drought. I've even made beer with the tank water.

No, I live in Detroit, Michigan right in between all the great lakes.  We've never had water restrictions.  We are surrounded by the largest source of fresh water in the world. 

EDIT: I just looked it up and apparently the city does place water restrictions on lawn watering.  Odd numbered addresses can water their lawn on odd numbered days, and the same for even numbers.  And you can't manually water between 6 and 9 am.  I don't think think these rules are actually enforced though, everyone seems to use however much water they want whenever they want. 

[MrsPete]

I'm surprised I'm only the second person to bring up drought.  A few years ago we went through 5-6 years of drought in my area, and we were on mandatory "water restriction".  We were not allowed to water lawns or gardens, not allowed to wash cars, asked to restrict household use.  Households who used more than X number of gallons per month were fined.  At the time, we were very concerned about the possibility of running out of water. 

In such a situation -- and it will come again -- having access to a barrel or two of water goes beyond dollars and cents.  Even if it's a break-even equation, I like the idea of having barrels of water on hand.  I don't have them now, but I do intend to have two barrels in the house we're building.  I am interested in self-reliance. 

[MrsPete]

Why not a rain water garden? See http://www.melbournewater.com.au/raingardens

I have never heard of this, but the idea is interesting!

[big_owl]

We have a backyard pond that's about 15ft dia with waterfall.  It's primarily for amphibians (frogs, newts, salamanders).  Usually rain is enough to keep it topped up.  I've always considered it a good 5k gal source of emergency water should TSHTF.  Rain barrels seem a ridiculously cheap insurance policy for same.

[Syonyk]

I've never even considered the financial aspects of rainwater storage.

It's better for plants, it's a good use of a local resource, and it's a good backup system.

I don't have it right now, mostly because I don't have any gutters installed on the new house yet, but I'll be putting in a few thousand gallons of storage (seasonal storage - rain in the winter and spring, use it in the summer).  I'll probably top it off with well water if it gets too low, since I plan to hook a fire pump up to it as well - our hillside tends to burn every few years, and while I'm going at resolving the local flammability (cheatgrass... ugh), I'd still like to have the ability to drench things in a hurry.

[MoneyCat]

This is a great thread. I had been thinking about getting rain barrels, but the OP is correct that the math doesn't work for it. If I lived in a desert climate, then, sure, it would be worthwhile. But water is so cheap and plentiful where I live that it's pointless to store any. I suppose if I ever get the urge to live off-the-grid then I will get some rain barrels but as things stand I'm not going to get any unless someone gives them to me for free.

[PAstash]

I am working on this system. So what I am planning to do is make a barrel for free/acquire one for free. Use a tarp that I already had. Stretch it out above the barrel to help collect the rain. situate it on a higher platform so the water is gravity fed to a trench that goes between the rows of the garden. This trench is lined with old gutter that I found. at each T section of the garden row I will cut a small a groove into the gutter. this will carry the water run off to the rows which are again slightly lower then the previous level.

Not sure how well this will work out.

[jacksonvasey]

I have a rain barrel, mostly for the novelty, and because having multiple barrels breaks some unwritten aesthetic rule in DW's head.  I just like having some backup water, and I also use it to make compost tea, since it has not been chlorinated, which might hamper bacteria culturing in the tea.

One thing I'm doing is reworking how the garden beds can passively absorb runoff.  You said you've already built the beds and don't want to redo them, which is understandable.  But you could consider placing beds in areas where runoff might be concentrated during storms.  I'm currently planning on digging a mulch pit next to my driveway, and trying to direct some of the runoff there into the mulch pit, to feed some perennial food plants around the perimeter of the pit.

I've also been dabbling with hugelkultur, which is where you bury rotting logs in a couple inches of soil, and plant your annuals in that soil.  Over a couple years, as the logs rot they become big sponges, and can act as a buffer, absorbing excess rain water, and letting it out into your plants' roots during drought.

I like the worm tubes, I might give that a shot, though I recently built a 2-bin worm/compost bin, so I'll probably stick with that til it rots.