Is A Water Tank Necessary?

[Valjean]

At my new older house in Bangkok we had the pump replaced. The pump takes the water directly from the street main and not off a tank. There is an older in/above ground cement tank but before the change of pumps that was not use and the pipes diverted direct to the pump.

Should I have a new tank put in? (I'm going to have the old one taken out and reorganize that area). If we don't have the pump then there isn't very good water pressure. I do wonder about the pump sucking water from the main however. Other than having a back up water supply and what I'd assume was more consistent water pressure is there a reason to have that tank?

Edited June 12, 2008 by Valjean

[ignis]

A water tank is not so much about the water but the electric..

My water tank is 2m high cylinder [have a detached house] on Condo blocks you see the tanks on the roof..

If and when the electric goes out you can still use water, if you are connected direct and the electric goes out can you still finish your shower? Wash your hands? Etc…Do you have power loss? Where I live electric goes out often

[Lite Beer]

A water tank is not so much about the water but the electric..

My water tank is 2m high cylinder [have a detached house] on Condo blocks you see the tanks on the roof..

If and when the electric goes out you can still use water, if you are connected direct and the electric goes out can you still finish your shower? Wash your hands? Etc…Do you have power loss? Where I live electric goes out often

Nothing worse than not being able to flush the toilet because of lack of water.

[lopburi3]

1. Pumping directly from mains should not be done. This was a prime cause of contaminated water here in Bangkok in past years and should not be happening anymore. The supply pipe can go negative pressure and you start to suck in ground water or the neighbors laundry tub.

2. You should have a holding tank and have mains feed that and use a pump to feed your home for higher pressure you want. Many people will also have a bypass so that you can feed home direction from mains when electric/pump fails.

3. The tank also serves as a reserve water supply for when there is maintenance and no water is being provided.

[Bagwain]

I have a water based business here in LOS.

What has already been stated is good.

Back up is the main issue.

I would also install a P.O.E (Point of entry filter) after the tank with Zeolite media.

This will give you usuable water and some protection in the case of the tank getting contaminated.

[Valjean]

1. Pumping directly from mains should not be done. This was a prime cause of contaminated water here in Bangkok in past years and should not be happening anymore. The supply pipe can go negative pressure and you start to suck in ground water or the neighbors laundry tub.

2. You should have a holding tank and have mains feed that and use a pump to feed your home for higher pressure you want. Many people will also have a bypass so that you can feed home direction from mains when electric/pump fails.

3. The tank also serves as a reserve water supply for when there is maintenance and no water is being provided.

Aside from the other good issues raised this one I really wondered about. This weekend buy that tank...

Thanks

[Crossy]

All good stuff ^^^

Do it something like this :-

Gives:-

1. Boost to pressure with pump
   
2. Backup water when supply fails
   
3. Water direct from mains when power or pump fails
   

You may want to add a means of draining the tank and a cutoff for the tank feed for cleaning or tank repair.

[Valjean]

All good stuff ^^^

Do it something like this :-

Gives:-

1. Boost to pressure with pump
   
2. Backup water when supply fails
   
3. Water direct from mains when power or pump fails
   

You may want to add a means of draining the tank and a cutoff for the tank feed for cleaning or tank repair.

Thanks this is great!

[Gary A]

Use Crossy's diagram and you'll have the best of both worlds.

[Valjean]

Some more questions:

What is an "isolation valve" and what purpose are these two? I'm clear on stop cock and check valve.

What is the reason for the alternative flow of water from the main to bypass the tank and pump? To ensure some water if there is no power? (my tank would be at ground level so no gravity feed)

I must say this is the most helpful and friendly forum on TV.

[PhilHarries]

Isolation valve, IME, is a simple gate or globe or similar shut off valve as opposed to the stop cock that prevents backflow in case of low mains pressure.

The bypass is there to allow water supply to be maintained in case of power outage or pump failure. Supply pressure at your taps may be lower but at least you'll have some.

I would also install an isolation valve in the bypass or you might get backflow through the pump and overfill the tank (depending on the type of pump and it's accessories).

Personally I'd prefer an elevated tank with gravity feed but we can't always get what we want..

[Crossy]

Isolation valve, IME, is a simple gate or globe or similar shut off valve as opposed to the stop cock that prevents backflow in case of low mains pressure.

The bypass is there to allow water supply to be maintained in case of power outage or pump failure. Supply pressure at your taps may be lower but at least you'll have some.

I would also install an isolation valve in the bypass or you might get backflow through the pump and overfill the tank (depending on the type of pump and it's accessories).

Personally I'd prefer an elevated tank with gravity feed but we can't always get what we want..

A couple of good points Phil.

A second check/non-return valve in the outlet of the pump (if it doesn't already have one) would prevent backflow overfilling the tank. I'm always for the automatic solution, the Missus would never work out what all the taps are for

'Stop cock' in this instance is the water companies valve, the 'isolation valves' are simple gate/ball taps so you can isolate and remove the pump for maintenance without draining your tank.

You're probably going to want a particulate (grit) filter on the supply to the house or in the incoming supply. Anybody got suggestions as to which would be best location? Or perhaps the belt-and-braces approach and have one in each line.

Edited June 13, 2008 by Crossy