Nick Neufeld wrote:Hi Shawn,
Did you install a rain cistern? I'm planning an off-grid cabin in Manitoba and would like to hear about your project and how it's working out. I'm hoping to use only rain and snow for domestic use. Not planning on digging a well.
Hi Nick, glad to hear of another Manitoban looking at these things. Unfortunately my project had to be put on indefinite hold due to health issues so I can't share any success stories or lessons learned, but I can share a bit about what I thought of over the past few years.
One thing to mention (mostly for non-Manitobans) is that in Manitoba most houses have a basement. Since our frost line can be 6-8 feet deep, if you're digging a conventional footing and doing 100% conventional building, continuing to dig out the basement and finish the space is the cheapest $/s.f. you can build. And it is better for heating than adding another story since the ground might be around 0 degrees C while the outside air might be -30 degrees C. So if you're digging a basement, one option could be to put some sort of cistern in the basement space since you are already excavating it. But then you're also giving up inside space which is usually at a premium. In my opinion, the only other option I would consider for storage in Manitoba is burying a concrete cistern. I hate to use the concrete, but you can't bury a metal tank and the plastic ones can't handle the hydraulic pressure of ground moisture very well if the tank is ever empty. Obviously though this depends a lot on the specific site and how the water levels are.
I think there are a few different strategies one could consider in MB:
1. Get enough tanks so that you collect enough water when it's warm to last you through the winter. Of course, if there's a dry year this is a challenge. But that's a problem with relying on rainwater anyway.
2. Figure out a way to collect moisture from snow during the winter so you need less tanks to store water. I think it's possible but I don't think it's very efficient. I have yet to come up with a strategy that I think would meet my criteria on this front.
Obviously this all depends on what sort of water needs you have. If you're going for a conventional home water usage, then you're going to need a lot more water than if you're going for something more frugal.
Something else to consider: We were originally planning on building a home with a roughly 900 s.f. footprint. But then we started talking about building a much smaller house - 240 s.f.. So as we were planning the much smaller house, we started to think that 240 s.f. is not a lot of roof catchment. And even with frugal usage, it might not always be enough. Maybe one day we'd get a shop built and collect rain from there too, but regardless, for nearly all situations, I think it is very good to have a backup plan.
One backup plan is to just dig a well and have that available if you need it. But that's costly. And, like I said above, where I was planning to build has a very high water table and I was concerned about toxins entering the water supply from nearby conventional agriculture. Of course a prudent step would be to test and see.
The other option is to haul in water from the municipal system. It's not the most sustainable strategy, but depending on your situation may function as an acceptable backup in case you don't get enough rainwater stored up.
Anyway, those are my thoughts for now. Best of luck with your project.