water harvesting in wet climates..!???

Little question here..

would you bother to even collect water when there is reassured precipitation? (I do not know the extents of it though..).
oh, and thee is a river flowing through the propperty (neither do I know if it dries up in summer- sorry, vague!).

Maybe stupid question.. but my intuition is that if you are going to change the roof, you might aswell adapt it for water caption?
Have a direct and reliable source to bycicle washingmachine, gardens, feeding a chinampa system or a lake, or creating energy... simply having a secure water source that you actually have in storage..
Or..?
(Maybe its cause I'm used to lack of water so I just see it as gold..)

Thank you for your thoughts !!!
Amanda

Hi Amanda, Welcome to Permie.

It is hard to say without knowing more about your specific site and climate but the general advice seems to be that there is no such thing as too much water catchment, although we might draw a line at catastrophic flood conditions! Here in the UK we have pretty much a wet climate year round but even here we need to occasionally irrigate in summer dry spells. Much of what I'm doing is trying to build the water holding capacity of the soil.

What is very helpful is if you can add your location to your profile information - you may find someone from your area who knows your climate well.

Mike

As with most things....it depends. How much water will you need? Just for household use, or do you plan to have a moderate garden, or perhaps a farm? If you have livestock, your water needs will increase. Can you legally use water from the river? Is the flow adequate year around that you would not impact landowners downstream? Does your area have a history of droughts? In case of fire, do you have access to plenty of water for fire control? Another factor is cost. Is buying water expensive or cheap in your area? Would it stay cheap?

I live in a rather moist area, 60-80" rainfall annually. But we have cyclic drought years, often 3-4 years of plenty of rain then 2-4 years of not enough. So stockpiling water makes sense here. Plus there is no water supply for fighting fires, so we need to maintain our own water storage for this purpose. I maintain three large water storage tanks, which on wet years like now, seems like incredible overkill and silly. But during drought I am immensely thankful to have those tanks.

I WILL NEVER DO A NON POTABLE ROOF AGAIN!!!

I always want the ability to capture and use the water. On this property my house is on the high ground (type 1 error, I know NOW) so roof water would be the only thing available without pumping.

Metal roofing is cheaper in the long run, fire proof, and just plain awesome.

The short answer - no matter how much rainfall you get, rain catchment is a good idea. There is nothing like a rain water shower!

The long answer - We live on a relatively remote section of the Washington coast where annual rainfall is about 70 inches/year. We have community well water, and although it is "legally" potable, it tastes terrible due to high levels of manganese and iron. I also believe it to be marginally safe biologically. We don't let our dogs drink it. We currently use the well water for washing and flushing the toilet, but all drinking and cooking water is filtered using reverse osmosis. About 1 year ago I installed an experimental independent rain capture system. Basically a polyethylene sheet mounted atop the garage feeding five 55 gallon poly barrels. I chose to build an independent system rather than capture rain directly from the roof for two reasons. First, the roof is currently covered with asphalt shingles so the polyethylene cover provides an essentially food grade collection surface. Second, we get a LOT of rain and our water needs are small, so a 10 ft x 20 ft rain capture area is adequate, at least as a first step.

Our lowest rainfall months are July/August when we average a bit more than 1 inch per month. This still delivers over 120 gallons/month, which is fine for drinking and cooking. Some of the winter months average around 10 inches/month which is a lot more than we can use. Also, we can presently only store 250 gallons. In winter months we also shower and do laundry using rain water.

A rain water shower is a true luxury so this summer we will triple the capture area to 600 square feet and double the water storage volume to 500 gallons. This should allow us to use rain water for just about everything, year round.

So far the poly sheet system has stood up well. It has stayed put through a couple winter gales off the Pacific in excess of 60 mph. Because our sky is overcast a lot of the time I expect the poly sheet will stand up for at least two years, maybe more, before it needs replacing. 600 square feet of poly costs about $70. A bargain considering the quality of water it delivers.