Comments Off on Rain Water Harvest System With A First Flush

The couple of days I got home before dark I was able to do some work on the rain water harvesting system.


Even though I had one in place, it was a make shift system and I was loosing many, many gallons of water every time it rained.

Plus I did not have a “First Flush” system in place to catch the contaminates before it dumped into the tanks.


What contaminates you ask, after all it’s clean rain water right?


My house like most is an asphalt shingled roof and every time it rains some of the particles from the shingles wash off into the gutter making their way to the bottom of the storage tanks.

Plus there is the dirt and dust that collects on the roof from the normal everyday wind. We also live in a farming community way out in the boondocks where they still spray the fields with airplanes. Even though they are careful, I am sure some of the chemicals still settle on the roof tops of our houses.


That is where the First Flush system helps out. It will collect around the first five to seven gallons of rain water and then bypass the flush system leaving the bad water in the pipe and dumping the clean water into the tank. The lingering heavier particles will still be able to fall to the bottom even during the bypass stage.

This system will reduce the build up of foreign matter in the tanks and increase the quality of the water.





The bypass is made up of 3″ pipe, two 2″X3″ adapters, a 3″ clean out, a 2″ sweeping “T” and an empty water bottle. This picture shows the bottle being placed in the bottom of the pipe then clean out cap is screwed back on finger tight.





When the water fills the pipe, the bottle floats and when it reaches the 2″X3″ reducer, it clogs the hole and the water is bypassed into the tank. After the water is bypassed any left over heavy particles will hit the bottle and still sink to the bottom of the pipe.


After the rain has ended, all I have to do is unscrew the clean out cap on the bottom and drain the pipe.





The Flush pipe is attached to the gutter using a flexible down spout.

Even though every rain water harvesting system should have a first flush, it will not collect 100% of everything. This water will be filtered enough to put on the gardens and to be used for the animals, but for the bathhouse I still want it to be filtered a little more.

Before it goes into the bathhouse, the water will be filtered using a hot tub filter.


Just wanted to share this. I thought somebody might need it in the future.

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