Rainwater Catchment
( from Monterey Greywater Group)

Since it only rains four or five months out of the year, in our Monterey County Mediterranean climate, we can only catch water for part of the year. But in that time there is more than enough rainwater for excellent rainwater catchment. This means tank(s) storage, at least 2500 gallons to last the usual long dry growing season.

• Rainwater catchment is simply catching the rainwater that hits the roof.

• The gutter system, on the eves of your house, channels the water towards your tank.

• The tank site needs to be very stable and is usually preparded with a base of decomposed granite or crushed stone (a cement pad is needed for tanks over 5000 gallons).

• Put the tank as close to the source as possible, to reduce the amount of piping necessary. ( Dealing with problems like trenching, and roots, and going under walkways can add a great deal of cost to a system. )

• The aesthetics of the tank site, are the final consideration. This is be easily be addressed by camouflaging the tank through various means, such as screens, plants and even an artistic paint job.

• A 2500 gallon tank is 8 feet tall and 8 feet across, but they are pretty light when empty, and they roll easily, so little ingenuity goes a long way. (The tank delivery, and placing the tank can be a little tricky. )

• To connect to the source, cut the gutter, install a diverter. (This device has a screen filter that sends the leaves, and debris, down the old gutter, and diverts the screened water out the side toward the tank.) This pipe leads to another filter, with the even finer screen. Both these screens are self cleaning and should be maintenance free.

• The fourth component is the First Flush system. It collects the first 10 gallons of water to come off the roof, and diverts it to the landscape. This is to keep the dust and pollen and anything else that builds up on the roof during the drier season from entering your tank. As more rain falls this system closes itself off and sends the cleaner water, into your tank.

• There’s an overflow outlet that sends the excess water, out of the tank when it's full.

• There is a water spigot on the side of tank for you to draw your water from, and often, even another spigot down lower, to drain any sludge that may accumulate in the bottom of the tank. And that's pretty much it.

• The obvious use for this alternative water supply is as irrigation for the yard and garden. ( But in a major crisis this could easily be treated for use as drinking water. )

• Cal-Am and the Monterey Peninsula Regional Water District have teamed up to offer a significant rebate, to promote the installation of these systems. They are willing to pay $25 for every 100 gallons of rain catchment system installed, up to 3000 gallons. This comes to $625 for 2500 gallon tank. A 2500 gallon tank is suggested because it's an excellent size for residential use, and seems to be offered for a much lower price than tank just a little bit bigger.

• This type of system is very sustainable; use no energy, last for decades, need little or no maintenance. And with the price of water skyrocketing, they’re a sound economic investment as well.