Harvesting Rainwater-Part Four

>> Monday, September 5, 2011

(If you would like to check out parts one, two and three here are the links:  Part One, Part Two, Part Three )

I mentioned at the end of Part Three that I had to take care of the overflow once the tanks were full.  My overflow pipe is installed on the opposite end of the tanks from where the water goes into the tanks.

IMG_0118In this photo you can see the 3” PVC pipe that comes out of the tank, runs to the side of the house and runs down to the corner where the roof washer is located.

IMG_0117The pipe turns around the corner and runs along the back side of the house, down to the end of the deck.  There it turns back to the right.

IMG_0110As you can see in this photo the pipe goes over half-way across the end of the deck and then turns again, going under the deck.

IMG_0113The pipe runs under the deck and into one of the two poly tanks that are under the deck.  These have been collecting the limited amount of water previously for use in watering flowers and garden.  I plan to run a pipe from these tanks in under the house and by using ball valves make it possible to draw from them if the main tanks should run empty.  The two poly tanks hold approximately another 950 gallons of water.

IMG_0124Here is pictured the pumping set-up.  It may be a bit unconventional but I have installed a 12 volt DC pump.  It is plugged into a converter that converts 110 volt AC to 12 volt DC.  Electrical usage should be less.  The blue tank is a 20 gallon pressure tank.  Instead of the pump coming on every time a faucet is turned on as is common with most DC pumps used in RV’s or on boats we will have several gallons of pressurized water to use from before the pump kicks on.

Some have been wondering, I’m sure, whether we can survive on what rainwater we can harvest.  Let us look at some figures.  The average rainfall for our county is a bit over 46 inches per year.  One inch of rain yields .6 gallons of water per square foot.  The roof of our house is 32 feet by 47 feet (the “footprint”).  That is 1500+ square feet.  Multiplied by .6 we find that one inch of rain will amount to 900 gallons of water.  At that rate it will take only about 3 and 1/3 inches of rain to completely fill the tanks, or the average rainfall would fill them almost 14 times.

Some figures found on the internet will tell you that the average person uses 60 gallons of water, or more, per day.  I know that figure is much higher than our usage.  Being quite liberal with my figures I  calculate that we use 40 or less gallons per day, each.  And, we will do some things differently knowing our supply will be limited at times.  For example, the reverse osmosis system we have for our drinking water is a water waster.  Depending on the system of course, but from 4 to 10 gallons of water goes down the drain for every gallon of filtered water you obtain.  We plan to quit using the RO system and use the Big Berky fulltime.

We plan to switch over to the cistern soon.  We have been receiving rain the last couple of days.  When I checked mid-day today our tanks were about 60% full and it is still raining.  We will keep you posted.


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