Water tanks

[Ralfredo]

Not surprising that there is a water shortage in Hua Hin; it is all in Big Boys tank!

[STEVE G]

Mine is underground and measures 8mtr x 4mtr x 2 mtr - no, we've never had a water supply problem

Wow, that's huge! 64 cubic metres, is that a common size? The houses I've lived in had tanks of only a few thousand litres, and I always thought that was the norm.

The tank at my house isn't that big but it's about 40 cubic metres, basically it's the base of my detached kitchen.
When we first built the house, it wasn't on mains water and we had to truck it in which is why it's so big.

[brianks]

If you have a tank and mount it above round the tank needs to have nontransparent walls in order to inhibit the growth of algae. I discovered this when I purchased a tank that looked like a DOS tank but was half the price. When it was delivered, I noticed I could see light through the walls. It didn't take long for algae to grow in the tank and then had to add bleach to the water to keep the algae growth in check. My current house has the more expensive DOS tanks with their nontransparent walls. Some tank mfg. line the walls of their tanks with a black film which stops the light leaking in.

[Nereus]

If you have a tank and mount it above round the tank needs to have nontransparent walls in order to inhibit the growth of algae. I discovered this when I purchased a tank that looked like a DOS tank but was half the price. When it was delivered, I noticed I could see light through the walls. It didn't take long for algae to grow in the tank and then had to add bleach to the water to keep the algae growth in check. My current house has the more expensive DOS tanks with their nontransparent walls. Some tank mfg. line the walls of their tanks with a black film which stops the light leaking in.

Yes, that is correct, "caveat emptor"! A quick test before you buy: shine a flashlight onto the side and make sure no light penetrates the wall(s).

I cannot see the sense of this configuration. Maybe it comes with a step ladder for when, not if, it gives trouble!
The only advantage that I can see is that SOME of the small pumps do not like a flooded suction, and will eventually lose the air cushion and short cycle.

dos tank 2.jpg (73.17 KiB) Viewed 1150 times

dos tank 1.jpg (64.16 KiB) Viewed 1150 times

[caller]

I noticed these when I added a 2nd tank to my house a few months back. I dismissed them imediately as impractical. Too much of an unknown, more exposed, new piping and leccy source required etc.

[VincentD]

Was trying to figure out how that would work too. In both houses in Bangkok, we have a check valve system installed together with the water tank. The pump is an on-demand pump, and will only work if the demand pressure is lower that the mains, and the check valves ensure I'm not pumping back into the mains, or drawing direct from the mains into the pump.
I have a 1,200 liter tank in one house, and a 750 liter tank in the other, more than enough for 4 people for a couple of days, and also allows for enough change to prevent stagnation. My two baht's worth..

[STEVE G]

^I just had a read of some translated ads for those DOS tanks with the pump on top and it seems it's purely for space saving and aesthetics.
There is a cover to protect the pump to make it look tidier and I suppose in a small property it could make sense.

[Nereus]

Was trying to figure out how that would work too. In both houses in Bangkok, we have a check valve system installed together with the water tank. The pump is an on-demand pump, and will only work if the demand pressure is lower that the mains, and the check valves ensure I'm not pumping back into the mains, or drawing direct from the mains into the pump.
I have a 1,200 liter tank in one house, and a 750 liter tank in the other, more than enough for 4 people for a couple of days, and also allows for enough change to prevent stagnation. My two baht's worth..

I am surprised that there is anywhere in Thailand where the mains pressure is sufficiently above the cut-in pressure of the pump, given that most of those small pumps have a cut-in pressure of around 2.5 bar. But the biggest problem with connecting it like that is the fact that all the crap in the mains water is running straight into the house most of the time!

Any check valve would need to be in the line after the mains meter and before either the tank or the house line, that line being common, to prevent flowback into the supply main. All of those types of pumps operate as "on demand" as the pressure drops at the consumer point. Most of the pressure switches have very little adjustment range, either cut-in or cut-out.

The pump being mounted on top of the tank makes no difference as to how it works, apart from that flooded suction that I previously posted. Both the inlet and outlet pipes to the pump are located at the bottom of the tank, the connecting pipes both simply being inside the tank. The water level in the tank is still controlled via a float valve. Many of the tanks have the fill pipe mounted internally like that.

Yes, it has some aesthetic value, not something Thais seem to concerned about!

[VincentD]

Nereus, you're correct about the poor water pressure, the pump is necessary to pump up to the upper storey, otherwise the wife would be throwing a hissy fit..