Monterey Rainwater Catchment

Rainwater Catchment For The Monterey Area

    Rainwater catchment, as far as were concerned, is simply catching the rainwater that hits the roof. This simple feat is performed by using the gutters to channel the water into a holding tank. Our Mediterranean climate makes this process little trickier than some areas. Since it only rains four or five months out of the year we can only catch it for this short time. But this still this is more than enough rainwater for excellent rainwater catchment, we just need a place to put it all. This means storage, and a lot of it, at least 2500 gallons to last long dry growing season.
   

The process of rainwater catchment is straightforward enough. First, the source of the water is examined. The roof of course is the place to start, but the location of trees and the debris they produce needs to be considered, along with the design of the roof as the hips and valleys, and how they channel water also needs to be taken into account. The gutter system becomes more important as they channel the water towards your tank. Next, the tank site needs to be chosen.

 

The tank site needs to be very stable and is usually prepped with a base of decomposed granite or crushed stone (a cement pad is poured for tanks over 5000 gallons). It's logical to put the tank as close to the source as possible. This reduces on the amount of piping necessary and all the problems that positioning the tank away from the roof creates. 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 last consideration, and can be easily be addressed by camouflaging the tank through various means, such as screens, plants and even an artistic paint job. The tank delivery, and placing the tank can be a little tricky. 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.
   

Once in place, the tank is connected to the source. The gutter is cut, and a diverter is installed. 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 yet another filter, with the even finer screen. Both these screens are self cleaning and should be maintenance free. After the second screening, the water is sent to yet another component that is unique to rainwater catchment.

This 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.
After this it becomes quite simple, 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. Rainwater catchment is a logical, reliable, alternative water source, that provides as much water as you can hold.

 

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. It could also have some very valuable benefit as a water source for flushing toilets, but this time this needs some more investigation.

Our local water shortage is such, that 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. I stress to 2500 gallon tank 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. These systems are 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.