Active Water Harvesting: Storing the Rain for Human Use
Active water harvesting uses pipes to move water and containers to store it. It can then be used for drinking water, to supply water for animals and livestock, or to irrigate plants. The most commonly used container is a heavy-duty plastic rain tank rated for potable water.
Rain Tank Tips
If you are applying for the Tucson Water rebate, your rain tank must meet the critera below to be approved.
A Firm Foundation
Tanks must be installed on a level pad like concrete, compacted sand, or gravel.
A Closed System
Tanks must be closed, meaning no light gets into the tank and all open areas (inlet and overflow) are screened to prevent insects and animals from getting in.
Safe Overflow
Tank overflow must direct water away from any load-bearing structural foundation.
Wet Inflow Tank Systems
In a wet inflow system, water comes through a pipe off of the roof and runs underground to the tank, which can be distant from the roof that is serving as the catchment area.
The pressure of water entering the pipe pushes water through the pipe and into the tank. Even when it isn't raining, there is always water in the underground portion of the pipe.
Wet inflow systems are useful when you need to place your tank far away from the structure that you are collecting water from.
Note that the inlet -- the place where water enters the pipe from the gutter -- must be higher than where the pipe enters the tank in order for a wet inflow system to work.
Dry Inflow Tank Systems
In a dry inflow system, water comes through a pipe off of the roof and runs directly into the tank.
When there is no rain, the inside of the pipe is dry.
Dry inflow systems generally need to be placed close to the structure that they are receiving rainfall from, but they require far less pipe and less digging than wet inflow systems.
Take a Mini-Tour of WMG's Rain Tanks
With over 15,000 gallons of water storage capacity, we are able to capture most of the water off of our roofs for drinking, taking care of our animals, and irrigating our garden.
Metal Rain Tanks
There are several main types of tanks: heavy-duty plastic ones, metal ones with internal bladders, and underground tanks. Learn a bit about WMG's 5000 gallon metal Pioneer tank, installed in 2023.
Tour The Living Lab
(34 minutes) In 2020, our Desert Living Home Tour was held virtually. Join Joaquin as he shows you the above and below-ground cisterns at the Living Lab, plus native plants, rain basins, composting toilets, and more!
Rain Tank Tips
Keep your tank clean and critter-free!
Keep the Big Stuff Out
Use some kind of debris filter to keep branches and leaves out of your tank. A rainhead or leafeater sits at the top of the inlet pipe, below the gutter, where it is easy to see and maintain.
Keep the Small Stuff Out
A first flush pipe helps prevent dust, pollutants, bird droppings, and other finer particles from entering your tank.
No Critters!
A pop-up at the end of your overflow pipe will prevent rodents, lizards, and mosquitos from entering your tank.
Drinking Your Rainwater
What does it look like to drink the rain? It could be as simple as a manual process with a high quality filter or a whole-house system. Let's take a look at some of the choices.
Rain Tank Tips
Your pipes and tank will last longer if you invest up front in some proactive care. Note that the diameter of your inflow and overflow pipes should be the same. If one must be larger, it should be the overflow.
Good Pipes
All pipe to rain tanks should be Schedule 40 PVC. Usually a 3 inch or 4 inch pipe is appropriate, depending on the size of your roof (catchement area). Make sure that your overflow pipe is at least the same diameter as your inflow pipe.
Protect Your Pipes
All PVC pipe above ground should be painted to protect it from UV light. Otherwise, it will sunburn and become brittle. You can paint it with spraypaint or house paint.
Protect Your Tank
If your tank is installed in a sunny spot, consider protecting it from UV light by painting it with elastomeric roof coating. You can add latex house paint over the elastomeric roof coating in whatever color you like to help your tank blend in--or stand out!
