Very low water pressure in house

Question

I have a single stored house with an overhead tank and a one inch pipe running down. In bath rooms this one inch pipe is reduced to half inch as all our bath room fittings come with .5 inch gauge.

I am not sure whether increasing the pipe size from one inch to two inch will increase the pressure, as its more affordable than buying a pressure booster pump.

for a 15 L bucket, its taking about 10 mins to fill it. having a shower with current pressure is a dream. I need to fix this at the earliest as its becoming more frustrating with out water pressure.

please let me know your thoughts and comments.

Thanks Subbu

Answer 1

Pressure

In a system fed from a header-tank, the pressure depends only on the height of the tank. To increase pressure you have only two or three options:

• Raise the tank higher.
• Install an electric pump (these are often used for showers)

If your header-tank is filled from a high-pressure municipal supply, you would probably get better pressure from that directly but in most places this would be a large job involving extensive knowledge of plumbing and local laws or codes. Your existing pipework and fittings might not be suitable for high-pressure.

Flow rate

The rate of flow is affected by

• pressure
• diameter of pipe
• length of pipe

Half-inch pipe is usually adequate for sinks, basins, showers etc.

Answer 2

in that short run: size of pipe has little effect on pressure.
You say the tank is overhead - Is this gravity feed?
In that case pressure is a result of gravity (height of water column) not size of pipe. If it is a pressurized system - a 1/2" pipe over the length you are describing would not decrease the pressure. Quite often low flow out of facets is a result of debris plugging up the aerator. what are you implying by "shower with current pressure is a dream" - seems at odds with the rest of your description. Or are you saying that the shower has good pressure and the sink facet does not?

Answer 3

There is nothing you can do to increase the pressure of a gravity feed system. Install a pressure pump on the shower line. They are automatic pumps that come on when you turn on the shower and do a great job.

Answer 4

To try and clarify some of the points above: The OP, Subbu, has a low pressure stored water system. The water coming out the taps and showers depends entirely on gravity for its flow.

To improve the flow (and 15 litres in 10 minutes is awful - you'd ideally want 15 litres in ONE minute) the single best solution is therefore to raise the height of the cold storage tank. DO THAT IF YOU CAN!

The flow will always be worse coming out of showers compared to taps (faucets) because the showerhead will be usually be held at a much higher level, so closer to the height of the cold storage tank. It's the DIFFERENCE between the height of the storage tank water level and the water outlet level that determines the amount of flow. Ie - if you were to keep lifting up your showerhead until it was at the same height as the tank (up in the loft!), then the water flow would stop completely. If, on the other hand, you took that showerhead down flat against your bathroom floor, you would have a much improved flow - as well as a mess...

Ok, if it's not possible to raise the height of the storage tank (it's already as high as it can go), then you should look at whether the pipes are routed as well as they can be - do they make the most direct route to the bathroom? Do the pipes have a slight 'fall' along all its length, or are there any horizontal runs? Do the pipes go first down to a lower level (say under your bath) before then coming back up to the shower? And - yes - going down to 15mm pipe is NOT good as this is a 'low pressure' system, so pipe sizing has a greater effect. All these things add additional 'friction' to the water flow, and - since it's driven at a low pressure anyway - this friction does make a difference. (Mains-pressure systems don't suffer like this at all - you can run it all pretty much in 1/2" pipe and up, down, and all-around...)

Ok, I don't think I'd entertain going up to a 2" pipe (that's huge), but an increase to 3/4" or even 1" pipe should help (although it depends on other factors as to how MUCH help).

Question for Subbu (although he's probably long gone) what water 'head' do you have? Ie - what difference in height do you have between the showerhead and the storage tank water level?

And, as said above, if raising the tank height and/or improving the pipe size/route cannot be done, then a pump is the only answer (without changing to a completely new, mains pressure system).