# Forum Home Renovation Water Saving Garden Ideas  Water Switch Problems

## Prometheus_au

G'day all,  
first post here so go easy if I'm in the wrong area (I did think about posting this in plumbing...) :Wink 1: . 
I have a Water Switch device hooked up to my pump, which is in turn connected to two water tanks. The Water Switch allows us to use Tank Water to flush our toilets and water our garden, but if the tank water runs dry, automatically switches over to mains water.  
Initially this was great, but our last water bill went through the roof, and we have full tanks and the pump is pumping tank water to the toilets - vegetable dye proved this. After running a few experiments I've discovered that the water switch device is allowing, albeit only a trickle, mains water to flow back through the pipe which runs to the pump and then back to the tanks.  It's as though the solenoid valve at the base of the water switch isn't coping with our mains pressure - which is quite high as we're in an estate that is only 25% developed.  
The idea I have to save the water switch device, as apart from the backflow problem it works fine, is to fit a check valve to its base - between the Water Switch and the Tank/Pump. 
My question is will this work? Will a check valve / one-way valve complement the water switch and get back to having the system save mains water and my water bill?  :Shock:  
Cheers all and thanks in advance....
Dave.

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## Bedford

> After running a few experiments I've discovered that the water switch device is allowing, albeit only a trickle, mains water to flow back through the pipe which runs to the pump and then back to the tanks.  It's as though the solenoid valve at the base of the water switch isn't coping with our mains pressure - which is quite high as we're in an estate that is only 25% developed.  
> The idea I have to save the water switch device, as apart from the backflow problem it works fine, is to fit a check valve to its base - between the Water Switch and the Tank/Pump.

  I can't find a parts list for these, but I'm pretty sure there is a non return valve in the fittings between the waterswitch and the pump, I'll have a look today. 
The fact that you're getting a trickle seems to indicate that it *is* there but maybe sticking or faulty.

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## Danny

When you say "Water Switch", I assume you have an Onga Water Switch. This particular product at least doesn't divert mains water to prime the pump as some others do and is rated for a maximum 1,000 kPa mains pressure. Is it still under warranty? 
 The problem can only be that the mains pressure is pushing water through  to the tank and this requires an open flow path. Debris jammed in the non return valve? To check this, you need to remove the unit and check it or take it to an Onga pump dealer.  
 The early (opposition) Davey Rainbanks had a design flaw in that there was no filter fitted between the tank and the rainbank. Sometimes a small bit of gritty sediment would get caught in the non return valve and this resulted in mains water continually flowing into the tank and then draining down the overflow pipe. I have often wondered if a filter was not fitted in recognition that a lot of sediment gets drawn into pumps from (wrongly fitted) low tank outlet valves and that sediment resuspension during a heavy rain event can cause filters to block. One will never know!  I am however surprised to see on the Water Switch owners manual a  diagram of a tank with the tank's top infeed positioned to direct water  towards the tank's low fitted outlet to the pump! OMG! 
The Water Switch has filters on both the pump and mains infeed. It is however surprising how sediment can build up inside pumps and pipe work,  the general assumption is that the flow of water will keep the insides clean but  this is not always the case. How often do you check the filters, particularly the one from the tank?  
If  a partially open flow path is not the cause, then this could then bring  the problem back to the mains pressure been above the recommended  maximum and the age??? of the Water Switch. It is recommended that the  mains pressure be set at 500-750 kPa and this would require the fitting  of a pressure reducing valve on the mains line. Some people however  find the lower pressure to be irksome and you may find 500 kPa annoying at  times. There is a move towards lower mains pressure to new estates and  you should check if your estate already has a reduced mains pressure and  if so, what is the pressure. 
If it is not a simple inspect and clean and (unlikely) found to need replacing, I would seriously look at reconfiguring your existing system. Having two tanks allows you to use one as the collection and settling tank with the pump drawing from the decanted transferred water in the second tank. Re toilet feed, the best system is to have two cistern valves, one for mains and one for rainwater. This allows you to simply switch between mains and rainwater via the individual stop cocks and the air gaps prevent cross contamination at any rate. Why use a pump to pump mains water?  
I have never liked these  things, they are expensive, unnecessary and just something extra that  can go wrong. Once you take the toilets out of the equation, the laundry  and garden can still use mains water when the tank is empty. A  simpler and cheaper option is the top up valve by Rainharvesting. It is  second from the bottom on the link below but all said and done, I wouldn't bother.   Rainwater Tanks for house and garden  
One  thing I would do is check the height of the tank's outlet that feeds  the pump and also have a look to see if the tank needs a desludge. I  would be looking to fix the problem rather than apply a bandaid.

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## Bedford

Here's the non return valve.

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## Prometheus_au

G'day all,  
Thanks for the replies.  
Unfortunately the item isn't an Onga - it's a generic which was installed by the builder and based on the information I have on file is here. 
The system does feed from the bottom of the tank, however there are filters fitted between the tank and pump and between the pump and water switch device, and these are clean - checked them yesterday. It is a self priming system.  
The water switch is no longer under warranty - just - it's 13 months old - so this is why I was asking if fitting a non-return or check valve to the water switch tank feed pipe would save the device. I don't fancy paying $400 plus for another one! 
Cheers
Dave.

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