Gravity Fed Water Pressure System

Have you got poor gravity fed water pressure, not sure if you need an emergency plumber or if it’s something to do with the hot water storage tank. Martin Smith explains everything you need to know when it comes to the pressure of water, when it comes to the height of your hot water storage tank.

In the picture to the right is a typical bungalow house, depending on where the tank is situated, your either going to have poor water pressure or high water pressure.

• I have low water pressure and my tank is in the cupboard?
• My tank is in the loft above, how do I get better water pressure?
• If my hot water storage tank is in the same room as the shower, can I get a decent flow of water?
• What is the recommend height of a hot water storage tank?
• If I have poor gravity fed water pressure, can I have a pump fitted?
• Does it make any difference if the pipe size was bigger on the water pressure?
• What happens if I only use 15mm pipe on the cold water feed instead of 22mm pipe?
• Does making the hot water tank bigger, give me more water pressure?
• Does using 2 bathrooms at the same time effect the gravity fed water pressure?
• Restrictions of gravity fed water pressure.

I have low water pressure and my tank is in the cupboard

If you have low water pressure and the tank is in the cupboard, there is nothing that you can do to get a higher water pressure unless, you either move the tank to a higher position or get a shower pump fitted. When water flows through the shower pump, the pump then kicks in for higher water pressure. Depending on the gravity fed water pressure from the tank, you may need to buy a special shower pump, but is no good for fixed showers, where the shower head is at the same level or more, to the level of water in the tank. The only way you can use a mixer shower on a low gravity fed water pressure tank within the same room, is to use a combined bath tap and shower hose but also use a pump. To operate the mixer shower, you will need to place the shower head as low as possible, so that the water flow comes out and the pump kicks in, however, it is important to make sure that there is good water pressure filling the hot water storage tank in the cupboard, as the reason being, the tank is most likely going to be under the manufacture guarantee when it comes to the minimum size to the storage tank. With the pump, you will not need to worry about the gravity fed water pressure.

My tank is in the loft above, how do I get better water pressure

If you have a hot water storage tank fitted just above the ceiling, within the loft, you will most likely going to get what is know as the normal gravity fed water pressure. A normal feed of water pressure will be between 2 to 3-meters of water pressure, which is measured from the top of the water level to the outlet of the water, which is about 1700mm below the ceiling to the bath (standard home built today).

If my hot water storage tank is in the same room as the shower, can I get a decent flow of water

As explained in the first paragraph, a fixed shower in the bathroom will be unable to get any water through if, it is below the water level of the tank in the airing cupboard. Any gravity fed water pressure within 1-meter is not recommended and would be classed as very poor water pressure.

What is the recommend height of a hot water storage tank

The height of the water tank should be a minimum of 2-meters head, however Martin Smith personally recommends the water pressure to be a minimum of 3-meters head in gravity fed water pressure and the higher the tank, the more gravity fed water pressure that will come through your taps.

If I have poor gravity fed water pressure, can I have a pump fitted

There are 2 different types of shower pumps that you can have fitted, one of the shower pumps has a negative amount of water pressure, where the other shower pump has to have a positive amount of water pressure at 1.5bar (This is not exact as different shower pumps can vary.

Does it make any difference if the pipe size was bigger on the water pressure

Having the pipes bigger, does not make the gravity water pressure any higher, however if the pipes are bigger and there are other water outlets on, then the restriction of water is lower, saving you from losing any water pressure.

What happens if I only use 15mm pipe on the cold water feed instead of 22mm pipe

If you use 15mm pipe and you have a 15mm outlet, then there will be no difference in the amount of water coming out if the outlet was at 22mm, for example the bath tap.

Does making the hot water tank bigger, give me more water pressure

Having a bigger tank only has a very little difference on the gravity fed water pressure, the reason is because, where out pressure to water will try to push outwards a little, having a bigger tank may not be noticeable, when trying to get more water pressure. The reason for having a bigger tank is not for the water pressure reasons, it is for more outlets and a higher flow of water require, saving you (the occupant) from running out of water very quickly.

Does using 2 bathrooms at the same time effect the gravity fed water pressure

Where there is no water restrictions and a 22mm pipe is used, having 2 bathrooms can only mean that you can use 2 taps at the same time within reason, however if the water flow was to be more than the outlet flow of 22mm, then there will be a restriction in the gravity fed water pressure. If the water pressure is high and the water was restricted to the outlets, then you can use more outlets, without the gravity fed water pressure being effected. The higher the tank, the more taps you can turn on, as long as there are restriction. A restriction can be the size of the outlet point.

Restrictions of gravity fed water pressure

Restrictions can be measure by a non restriction with an open ended 22mm pipe and how many liters per minute. If a standard 2-meter head gives a flow of 10-liters per minute, where the restricted tap gives 5-liters per minute, then the restriction is 50% = 2 taps with no loss of water. By putting the tank higher and giving 20-liters per minute, this then means, you can run 4 taps with no restrictions.

If your an occupant, that would like to have a recommended emergency plumber, that knows about restrictions, then give us a call and we will do our best to help you in your need, as a nation company, we are able to send out an emergency plumber to attend to your needs.

If your an emergency plumber, that would like to visit our plumbing register and also has knowledge about the different water pressures, then please register your details with us. If you feel that there is something missing here and could include any further information for gravity fed water pressure, then send is an email to emergencyplumber@me.com