The Issue of Rain Water Catchment

Hardly a week goes by without someone suggesting that I set up some rain barrels and capture some rain water. I had a similar notion when I first got the land last year, but I’ve since discarded it as being mostly unfeasible. But, since it keeps coming up, I figured I’d write a post describing why it’s probably not worth the trouble, at least for now.

At first glance, capturing rain water seems like a simple and obvious idea, given my lack of any other local water source. The area I’m in gets over 30 inches of precipitation a year, mostly between the months of October and April. During the warmer months, though, it’s generally very dry. This year has been a bit of an exception, with two very heavy days of rain so far already, but the average precipitation for the whole month of August is less than a third of an inch (although, I suspect the median rainfall for the month is more like zero, with exceptions every few years bringing up the mean).

So, what’s wrong with rain water catchment? The main problem is that most of the precipitation comes down during the colder months, and when I say colder months, I mean freezing months. Last year, lows in November were already falling to the low 20s F, and during the winter months, single digit lows are a regular occurrence. Last winter, it apparently got cold enough that a bottle of soda I’d left in the utility trailer had exploded, and some of my 2.5 gallon water containers had also been damaged. So, freezing weather creates, as far as I can foresee, two problems.

The first problem is that whatever container I collect water in has to be able to withstand freezing. The rain catcher I ended up using for my water tower specifically says that it needs to be emptied before frost. Other rain barrels and water tanks might be sturdier, but even if the container can contain freezing water without bursting, there’s still the fact that big chunks of ice could be difficult to work with if I wanted to use that water during the winter. One possible solution would be bury the water containers below the frostline, but that really complicates what should be a simple solution.

The second problem is that much of the precipitation comes down as snow. While rain can be captured off of my hut roof fairly easily, snow might be trickier since it obviously doesn’t flow the way water does. It’ll first accumulate on my roof, compact, maybe even freeze into ice, then eventually slide off in big heavy clumps. These clumps could come off the roof with sufficient force to either tear off the gutters, or fly right over them. I could create a surface with a nice gentle grade where snow can accumulate and stay without falling off as it gradually melts, but that still leaves the aforementioned issue of the water having to be stored somewhere where it won’t freeze.

These problems (and possible solutions) are further complicated by the amount of water I’d need to make the whole solution worthwhile. This summer, my garden used at least 25 gallons of water a week, and I used another 10 or so for drinking and bathing, for a total of about 35 gallons a week. If we say the dry season lasts 6 months (which is being generous), that’s 26 weeks X 35 gallons = 910 gallons. And trying to bury a 1000 gallon tank, even partially, is no easy task. Besides, a tank of that capacity isn’t exactly cheap; rule of thumb is roughly $1 per gallon for a good tank. On top of that, if I need to build a separate water catchment surface other than my roof, I’d need a surface over 80 square ft in area assuming I manage to capture 20 inches of precipitation, which is probably optimistic (the math: 20 inches ~= 50.8cm, which means 5.08 liters per 100 square cm, or 508 liters per square meter, so to get 1000 gallons or 3785 liters, I’d need 3785/508 ~= 7.45 square meters ~= 80 square feet). And that’s just to barely cover my current needs, which are pretty minimal. I guess I don’t have to try and cover all my needs this way, but seeing how little work it currently is for me to haul water from town, I’d want a replacement to be significantly less work to justify the up-front cost.

Of course, compared to digging a well, which could cost me over $10k, a 1000+ gallon water catchment solution could still be cheaper. So I wouldn’t dismiss the idea entirely, but nonetheless, I don’t think it’s quite as simple as most people seem to think it is. Or maybe I’m over-thinking this. Has anyone successfully setup water catchers in similar climates?