[david wood]

Hi need help again  my water pressure is 60 psi from my outside tap  but is showing between 15-18 psi before my membrane  so it's making pure water very slow  tap water 75 after ro is 2 so it's working ok apart from the pressure ?

[Afterglow Window Cleaners]

have you changed the pre filters?

[david wood]

Yes changed them but it was slow before I put new membrane and filters in

[david wood]

It used to be pretty fast at my old house but since I've lived here it's slow

[Afterglow Window Cleaners]

Have you measured the pressure just before the pre filters, could the pressure drop over a long length of hose before it gets to your RO

[Don Kee]

Check your water flow... (If anything, get a jug and see how long it tends to fill to capacity)

Theres a difference between flow and pressure
think garden hose, switch the tap on and the water flows out your hose but if you put your finger over the end, then water jets/sprays...

Same flow, different pressure

You may have good pressure but 40/40's need a good amount of water running through them, and it may be crap at your new house...?

(May not be, might just be a blocked pipe or air lock)

[david wood]

Thanks for that the outside tap and the kitchen tap are  slow  would a booster pump sort it out it takes me about 8 hours to make about 500 Lts of pure water

[SeanK]

I know this might be a stupid reply but have you checked that you mains cut off tap is fully opened.
Try and check a neighbours water pressure/flow just to make sure there's not something wrong with your plumbing.

[martin hulstone]

A booster pump would definetely help, I have the clarke 240e that most people on here seem to have and i produce about 250 litres an hour at a 60 waste 40 pure ratio.

[Spruce]

I'm expanding on Don's advice on an earlier post.

I would start at the tap.

Is the poor flow and pressure just at that tap or does it also apply to the cold water taps in the bathroom and kitchen?

At that flow rate I can't see your toilet filling very quickly or the water will take ages to fill the bath.

If the flow is better from these other taps, then the problem could be at the point were the outside tap is plumbed into the main house pipe. (most outside taps are taken from pipe under the kitchen sink. They may use a special self drill clamp - such as this

http://www.screwfix.com/p/outside-tap-kit-brass-15mm-x/33139?_requestid=197859#

It could be there is a problem as the hole is too small or the tap hasn't been opened properly. This could also apply if the outside tap feed is taken from the washing machine supply.)

Here is a review from someone who fitted one of these.
""I am a plumber and bought this to 'save time' on a quick installation...wish i hadn't bothered. You get everything you need and decent price however had 3 problems -check valve was faulty so initially didn't work at all -near impossible to tighten up onto a pipe for the supply, the fitting kept moving and hence leaking -very poor flow rate, half what customer was getting on his other outside tap Only give it 2 stars as is decent value"

If your water flow is poor everywhere, then the next place to try is the tap under the kitchen sink. Is that fully open? There could also be the possibility that the water has been 'turned off' in the street. The previous tenant my not have paid the water bill so the water board turned the water off. (They aren't allowed to completely stop the supply.)

Do the neighbours also suffer with low water pressure? - just knock and ask is the best way to find out.

[Shane sharples]

I once had a dodgy plumber who fitted the actual stop tap the wrong way round and the pressure was completely rubbish. Got another plumber out and he showed me the arrow on the side of the stop tap should be pointing upwards, not downwards lol , changed the stop tap the right way round and water pressure back to normal 

[Ian Lancaster]

The thing everybody forgets is that the pressure at the tap (or wherever your mains supply comes from) is not the same as your pressure at the membrane.

Why?

If the only way the water could go is through the membrane,  then the pressure as it hits the membrane would be the same as it is coming out of the tap.

BUT you have an 'open' route - the waste water.  As this is a 'straight through' run, water is diverted away with little resistance to its movement and so the pressure drops.

If you have (say) 60psi at the tap and only 20psi at the membrane the way to increase that pressure is to restrict the waste so more water is forced through the membrane.

If you had a half inch pipe from you tap going into the membrane housing and then an unrestricted half inch pipe from waste at the other end of the housing the pressure at the membrane would be nil.

[david wood]

Thanks for all the info . Checked the stop tap outside the drive way that's full on then asked next door to connect my ro to his outside tap and it sprung into life  reading 37 psi on my ro  my outside tap looks really old  so  I think my next step is to ring a plumber