Rain water harvesting is a simple way to save money on utility bills and conserve water to help protect the environment. Properly-functioning gutters are the first component of a rain water harvesting system.
For a Simple Rain Water Harvesting System
The least complex rain water harvesting system involves a rain barrel, which is simply a (55-gallon or larger) storage barrel made of wood or polyurethane that is placed underneath the downspout opening. It’s recommended that you set the rain barrel on top of a short platform, like a large wooden crate or a few concrete blocks.
Step 1: Start by measuring the height of the barrel and the platform and then adding an inch or two. This is the height from ground level where you will cut your current downspout.
Step 2: Position the rain barrel under the higher downspout opening, and trace a hole in the top of the barrel into which the water will flow.
Step 3: Draw another opening high on one side of the barrel, and another one low on the front side.
Step 4: Use a jigsaw to cut the top hole carefully, then cut or drill out the bottom hole to the size that matches a spigot. Do the same for the top/side hole to match it to an elbow or length of PVC or aluminum overflow pipe.
Step 5: Thread the spigot into the bottom hole and place the overflow pipe in the top/side hole; and use sealant or caulk to hold each one in place.
Step 6: To test your rain barrel, spray water from a hose into your gutter and ensure that it flows into your rain barrel without leaking at the top or bottom.
For a Larger or More Complex Rain Water Harvesting System
You can also configure your rain water harvesting system to store larger amounts of water in a polyurethane or metal tank.
After removing most (or all) or your current downspout, connect a large PVC pipe to the downspout opening. When connecting the pipe to the storage tank, make sure that it continuously slopes downward so that gravity allows water to flow into the tank. Also, you should install a shutoff valve near your home so that any water in the pipes won’t freeze in the winter.
In addition, the rainwater harvesting system should have a filtering apparatus of some sort. Gutter Helmet gutter protectors can act as this "first flush" to prevent dirty particulates from invading your stored water. Another alternative is a roof washer, which is a vertical length of pipe connected to the main PVC channel. The roof washer is connected with a valve so that the initial (dirty) runoff water fills up the vertical pipe, then opens the valve to allow the clean water to flow into your tank. The roof washer is emptied after each storm.
All that’s left is to attach the main PVC pipe to your storage tank, fit the tank with an overflow pipe, and attach a spigot at the other end. Larger volumes of stored rain water can be used for irrigating multi-acre land tracts, power-washing tasks, or even cleaning clothes or filling toilet tanks.