280 Cloud Cover Days...and still a drought
This is really about one of my many obsessions... catching water. That and canning. But that is another post to be sure....
Seattle gets 280 Cloud Cover Days a year, according to Extensions old friend George P. That is a lot o' cloud, but not really a lot of moisture through our growing Season. We generally get about 2 or so inches from July 5th- Oct. 1st. Yet veggie gardens require a lot of water. So, if it doesn’t rain regularly, through the summer, what do you do? Funny you should ask, build a water catchment system.
Water harvesting can be as simple as a rain gutter directed into a barrel or as sophisticated as a buried tank pump systems. Diverting a drain from the gutter to a barrel is easy. I had one on each corner of my old house, that meant 200 gallons and no plumbing required.
For every square foot of roof, you can collect a little more than a half-gallon of water per inch of rainfall. COOL! Seattle gets around 40 inches of rain a year. That means if you live in a small house, like a 1,000 square foot roof, you can collect 20,000 gallons. (.5 x 1000sf, x 40) I know what you are saying, I don't need 20,000 gallons of water, especially when the ground is already saturated in the Seattle winters.
There are two really important things to realize in the above, 1. How little rain you need to collect a LOT of roof water and B. What a HUGE problem surface water management is. The Puget Sound forests used to be a big sponge that filtered virtually all of the rain before it hit the Sound, now with roofs, roads, etc, it collects all the pollutants and dumps unfiltered into the Sound. So...lets catch it, use it and filter it through our gardens!
A basic system involves a series of gutters connected to conduits and as big a tank as you want or can afford fitted with a faucet. You can let gravity do its work provided the tank is on a stand, or you can use a submersible pump. It’s not a bad idea to empty and clean the tank each year. Be sure you support the tank adequately – just one gallon of water weighs around 8 pounds. An average Barrel is 50 gallons, so you do the math. :-)
Moss, bird poop, general detritus from your roof needs to be filtered. Downspouts, gutters, or the tank opening can be fitted with screens to keep large debris out of the system.
Considerations:
Mosquito Dunks (a bacteria that kills larvae) or a screen that prevents Mosquitoes is a must. Over flow also needs to be managed. I have had drains near the top that have drained into another barrel, and then onto a soaker hose spread throughout a bed. I have also had it drain into a French Drain.
