I recently had a mazuma external water filter fitted at home, however, I was a little concerned about position (not to mention the incorrect install) After I noticed they had mixed the clean filtered water with the non-filtered from my tank, and hoping I'd resolve it by calling another plumber to rectify the simplest of problems with a diagram I provided that a KG student could follow who comically plumbed it in the exact same fashion but in a different location on the pipes, I decided to do it myself.

One thing I did notice which the plumber obviously didn't is that the pump is fed by the pressure from the main supply and the tank in a T junction and if one or the other is shut off it will not switch the pump on which may explain why the plumbers cheated, as there wouldn't have been enough pressure from the tank to the filter and then to the pump.

As the pump relies on pressure from both mains supply and tank, if I install the filter at the pump inlet I am concerned there will not be enough pressure.

So my question is should the filter be positioned after the pump or before?

Edited October 12, 201510 yr by BBJ

After the pump, also the main water should only fill the tank, no "t" junction

The pump should pull from the tank - not from supply line - illegal and a danger for everyone.

Illegal and dangerous, can you expand?

So to clarify, this configuration would be Illegal? If so, disgusting considering it is a brand new development.

At present, my filter is situated on the exit of the tank which I have bypassed as it is filtering both filtered and unfiltered simultaneously.

Are you sure that is drawn right? Mains should have alternate path to go to output side of the pump (line for house use). The idea was to provide water without electric power (your pump would be turned off when tap from main supply was on allowing flow to pump). This is not how it should be plumbed - should attach at output of pump side with either an on/off valve or automatic to allow flow when mains water pressure is higher than home pump water pressure.

I believe this is " Crossy's " diagram.

Yup, that's one of mine.

The NR valve in the bypass allows one to use city water pressure when the power is off on order to have at least some water.

Just done a test. Turn all valves off from tank and let run for 15mins prior to the diagram. Unplugged the pump and I still have a supply of water as you described. In that case I need to find the incoming supply and connect a valve to shut it off as I don't want it contaminating the filtered water.

At the outlet of the pump I have 3 valves for lower and upper floor plus garden. I assume there may be a connection under the turf as there is no valve to be seen.

Thanks for the info in the meantime.

Edited October 12, 201510 yr by BBJ