Rain catchment and storage
I want to use the rain that lands on my roof
A catchment system is a roof, a route and a tank. Most of the design is the route.
Rain runs off a metal roof almost completely, off a flat adobe roof through its canales and scuppers, and off a shingle roof with some loss. We start on the roof, find where the water leaves and lead it to one place. Everything after that, the screen, the first flush, the tank and the overflow, is sized to what the roof can actually deliver.
The parts
What a catchment system is made of
Gutters or canales
They gather the roof's water at one or two points. On a flat adobe roof we work with the canales you have.
Screens
A leaf screen at the gutter and a fine screen at every tank opening keep out debris and insects.
First-flush diverter
It sends the first minutes of a storm, which carry the roof's dust, to the ground instead of the tank.
The tank
Opaque, screened and vented, buried below the frost line or insulated above ground.
The overflow
When the tank is full the extra goes to a tree, a swale or a ditch, never to the foundation.
Hose bib or pump
Gravity can feed a garden hose bib. A pump and pressure tank feed the house.
From tank to tap
Water inside the house needs pressure
A tank on a hillside can feed a garden by gravity. For a kitchen or a bath we add a pump and a pressure tank, and for any tap you will drink from, the treatment on the Treatment and testing page. We draw the pump, the pressure tank and the electrical need on the same sheet, so the electrician sees it before the trench is open.
What we draw
Pump and pressure tank sized to the fixtures
A shutoff and a drain at the tank
A tap you can use if the power fails
Rain catchment
About tanks, roofs and winter
How big a tank do I need?
That depends on your roof area, the rain you actually get and the water you will actually use. We size it from those three, not from a catalog. A bigger tank only helps if the roof can fill it.
Will the tank freeze in winter?
A tank buried below the frost line stays liquid. Above ground, we insulate the tank and wrap or drain the lines that can freeze. We choose between them on your site, your budget and how you use the water in January.
How much upkeep does a system need?
Plan on clearing screens and the first-flush diverter a few times a year, and changing filters on the schedule we write for your system. We leave a one-page maintenance sheet at the tank.
Does a flat adobe roof work for catchment?
Yes. Water leaves a flat roof through canales or scuppers, and we catch it there. We check the roof surface first, because some coatings and tar leave a taste in the water, and that decides what the water is good for.
Start with the roof
Text us a photo of it and tell us the town. We will tell you what the visit covers.