A Medium Sized Rain Water Collection System -- Water Delivery

This page covers the simple system used to deliver water from the tank to the garden.

 Water pump for rain harvest system

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Water Delivery

The water delivery system takes water from a penetration near the bottom of the tank, and routes it via 1 inch diameter PVC pipe to a small pump that is used to pump it over the garden area using a regular garden hose.

tank outlet

As the picture shows, the bulkhead fitting going through the tanks wall, and the 1 inch outlet line hooking up to the bulkhead fitting via a reducer to take it down to 1 inch.  A shutoff valve (the only one) is provided here near the tank to turn the water off.

The bulkhead fitting came already installed on the tank, which is a good thing as it would have been a pain to add.  So, order your tank with the fittings you want.  The "manhole" in the top of the tank would allow a VERY skinny man to get down into the tank and do the installation from the inside, but not much fun.

If you do add your own outlet hole, keep it up off the bottom of the tank a little as it might tend to fill with sediment if not.

We decided to use a small pump to get a better flow rate at the garden end of the outlet pipe.  I think that when the tank is full it might do OK without a pump, but its going to get very slow as the tank empties.

pump for rain harvest


The pump we used is an inexpensive Wel-Bilt from Northern Tool    It says that its a half horsepower, has 110 ft of output head, and will pump 720 gpm.  I've not confirmed these specs, but it does nicely for watering the vegetables.   The pump is not self-priming, so the pump must be located so that the case fills with water from the tank by gravity.  The inlet and outlet fittings are standard 1 inch pipe thread and work fine with PVC pipe to threaded adaptors. 

The pump price was about $50.  This is certainly not a deluxe pump, but the reviews were good and it seemed like a good way to start in that we were not that sure about exactly what we wanted.  So far it has worked fine.

The pump is hooked up to the 1 inch PVC line from the tank using the type of PVC union that can be coupled or uncoupled by hand.  This will allow us to use the pump in other places and to keep the pump inside for the winter.  The union has an O ring and should be good for quite a few coupling and decoupling.  The pump inlet and outlet fittings are standard 1 inch threaded fittings and adapt easily to the PVC pipe.

On the outlet side, we used a PVC elbow to get the flow in the right direction, and then used an adaptor to go from the standard pipe thread to a garden hose thread. 

We positioned the pump close enough to the garden so that one regular length of garden hose would easily reach all of the garden and the nearby trees.  This is why the pump is located a ways away from the tank.

The pump is installed in this little plywood shelter to keep the rain off it.   Its very quick to hook up and remove with the union fitting.  The 1 inch PVC lines comes directly from the tank outlet, and the grey garden hose goes over to the garden for watering.

pump shelter

I added an electrical outlet on the outside of the shop to plug the pump into without an extension cord, but it works fine on an extension cord as well.

Pretty simple. 

Go on to installing the water overflow system...

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Comments or questions...?


Gary July 5, 2011