Will this rainwater catchment system work?

Hey everyone!

I've attached a photo of the current design I have for our rainwater harvesting.

From the tanks to the ground roof (I'm building a roof raised on cinder blocks because we are living in a tiny house, not enough catchment area), it's about 150' with a 4.5 ft elevation change. Because of that I will have to bury the tanks about 4ft down. The tanks are 8ft tall.

The pump and pressure tank will then be about 4-5' above the bottom of the tank.

I'm curious if the pump will be able to suck the water out of the bottom of the tank like a straw when the level gets below the level of the pump.

Do any of you have any recommendations for a pump and pressure tank? I'm not sure what I should be looking for.

Cheers,

Derek

It seems to me it would be more useful to put the roof on a structure like a small pole barn so you can use it to store stuff, an outdoor eating or working area.  Can't have too many covered outdoor spaces around the farm.  This way you wouldn't have to go to the trouble of burying the tanks. Not all tanks are made to withstand the stresses of burial, so you might need to buy special tanks, which would be even more expensive than normal tanks.

Tyler Ludens wrote:It seems to me it would be more useful to put the roof on a structure like a small pole barn so you can use it to store stuff, an outdoor eating or working area.  Can't have too many covered outdoor spaces around the farm.  This way you wouldn't have to go to the trouble of burying the tanks. Not all tanks are made to withstand the stresses of burial, so you might need to buy special tanks, which would be even more expensive than normal tanks.

I could dig out the tanks but not backfill completely so they aren't actually buried.

The purpose of building the roof on blocks is because it's going to be quite large. 2000+ sq ft. We live in southern Arizona and get 11-14" of rain per year so we need the catchment area.

Doing a pole barn is definitely a consideration but it would add tremendously to the cost and difficulty of building it.

Here is one other option



The water tanks and the pump/pressure tank won't need to be buried. The pressure tank/pump especially.

Sometimes people will put the roof over their house for extra cooling.  I think people most often do this with mobile homes.

We have a system with partially submerged 5' deep cisterns and the 3/4 HP pump is located about 1' above the top of the tanks (so about 2-3' above the surface of the water).  The Pressure Tank is located above the pump by another foot or so - thus it is about 3-5' above the cistern water level.  System has been in place and plumbed for a week now without issue.  The trick is having hoses into the tanks which have a check valve to prevent the water running back into the tank once the pump kicks off.  Without check valves, you can't keep the above water pump primed.

Derek Howlett wrote:
The purpose of building the roof on blocks is because it's going to be quite large. 2000+ sq ft. We live in southern Arizona and get 11-14" of rain per year so we need the catchment area.

The roof itself is going to be the majority of your cost, putting it up on poles won't make it all that much more expensive but will have MANY advantages.  As Tyler mentioned, putting the roof over your tiny home will make you house cooler, AND it will add a lot of outdoor living area.  You could put a kitchen area out there, may be some seating, etc.  Plus if you want to grow food, many things will grow better in AZ if they are shaded (at least part of the day) from the sun, at least during the summer.
Then you wouldn't have to bury the tanks, you could use them as a partial wall on the sheltered area, and wouldn't have to buy all that pipe from the roof to the tanks.  Having the tanks higher will add some water pressure going into the pump so it won't have to work as hard and that will save you energy.  In fact for many things you could just use gravity for pressure.

The savings in work and 150 foot of pipe will go a long way towards paying for the poles to raise the roof.

I would make it so the sun can shine on the house during the winter, when it's lower in the sky, this will help heat the house.  I'd also use the east side of the shelter for veggies, etc.  That way they will get full sun in the morning, while it's cool, and then shade during the hot afternoon/evening.