Household water pump

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uppynz

51 posts

Master Geek

#311037 9-Dec-2023 15:07

We've recently had a new build completed and have 3 X burried water tanks. When the water tanks were installed, it was pouring with rain and the tank installers were unable to join the 3 tanks at the base to balance them. They have joined all three tanks at the top with 100mm pipe, so the first tank fills up, overflows to the next to fill, and then the third.

The pump has been set up to draw from all 3 tanks, which has seemed ok initially over winter when the tanks were full. Now we are getting lower (50%) my impression is that the pump is struggling to either keep prime or pull the water up from the 3 tanks, resulting in lower flow and pressure.

I've read the installation manual for the pump provided and it clearly states do not use multiple suction pipes and tanks need to be connected at the bottom, drawing from one tank only to maintain balance in tanks.

Is there an obvious solution here? I suspect as summer sets in and water level drops further, the pump will struggle more.

pih

649 posts

Ultimate Geek

Lifetime subscriber

#3170080 9-Dec-2023 16:17

Can you not just add isolation valves to each of the intakes so you're only drawing from one at a time? One other thing to check is that the intakes are not getting clogged. They should have prefilters (probably one for each tank) and if these are clogged or you have some air trapped in the intakes then it may be harder for the pump to lift the water. Give them a clean and fully re-prime before you try anything drastic.

CYaBro

4583 posts

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#3170100 9-Dec-2023 16:56

If it were me I’d be going back to the plumber.
If that’s the instructions for your pump and they have in fact installed it with multiple suction pipes then it needs to be installed correctly.

Opinions are my own and not the views of my employer.

uppynz

51 posts

Master Geek

#3170118 9-Dec-2023 18:20

I do have the option to isolate all 3 tanks at the moment. Does seem somewhat better only on one tank, but still not great, which in itself may point to a pump issue. It would be annoying to have to to turn valves on and off albeit not that often, but the way the tanks fill up when it rains provides a limiting factor as well as the first one overflows to the second and third so I could easily end up with two empty tanks and operating on one only, which we have started to see recently as the rain dries up.

The plumbers are coming back early next week for another reason so I'll have a discussion with them. Air getting in was my other thought. There are two areas for the plumbers to check that I'm not sure on, bit otherwise all pipe joins and elbows seem fine.

k1w1k1d

1519 posts

Uber Geek

#3170143 9-Dec-2023 19:37

Have they installed the bottom balance pipes as required in the pump instructions? This needs to be done.

I would suggest that the balance pipes have taps fitted so that any tank can be isolated for maintenance, or if it develops a leak etc. Don't want to lose all your water if one tank leaks.

Collecting rainwater is fairly common in Australia, so might be an idea to search some of their tank manufacturer sites for advice.

tweake

2391 posts

Uber Geek

#3170167 9-Dec-2023 20:44

uppynz:

I do have the option to isolate all 3 tanks at the moment. Does seem somewhat better only on one tank, but still not great, which in itself may point to a pump issue. It would be annoying to have to to turn valves on and off albeit not that often, but the way the tanks fill up when it rains provides a limiting factor as well as the first one overflows to the second and third so I could easily end up with two empty tanks and operating on one only, which we have started to see recently as the rain dries up.

The plumbers are coming back early next week for another reason so I'll have a discussion with them. Air getting in was my other thought. There are two areas for the plumbers to check that I'm not sure on, bit otherwise all pipe joins and elbows seem fine.

how much pressure is it loosing? your going to loose some as the tanks lower. rule of thumb is pumps push better than they pull. i would check the screens on the foot valve are not clogged up. you can get that if you get a lot of leaf litter or bird nests washed into the tanks. i highly recommend an overflow that is piped down to the bottom to suck the crap off the bottom.

how big are the tanks ?

is the pump variable?

Ge0rge

2052 posts

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#3170192 10-Dec-2023 00:55

CYaBro: If it were me I’d be going back to the plumber.
If that’s the instructions for your pump and they have in fact installed it with multiple suction pipes then it needs to be installed correctly.

Or get them to replace the pump with one that can handle drawing from multiple suction lengths - probably be easier than digging the tanks up to connect the lower ports - although the "it was raining" excuse sounds pretty weak to me, I'm not sure how rain would have stopped them threading some connections together.

For what it's worth, I have three tanks. Rain drains into the first one, and it is connected to the second at the top of the tank - first tank needs to be full before the second gets any. Second and third are connected at the bottom so they balance, and the pump draws from tanks two and three. In this way, I always have a reserve of 25,000l if anything happens, and it doubles as a firefighting reserve that remains full.

uppynz

51 posts

Master Geek

#3170212 10-Dec-2023 07:48

Ge0rge:
CYaBro: If it were me I’d be going back to the plumber.
If that’s the instructions for your pump and they have in fact installed it with multiple suction pipes then it needs to be installed correctly.

Or get them to replace the pump with one that can handle drawing from multiple suction lengths - probably be easier than digging the tanks up to connect the lower ports - although the "it was raining" excuse sounds pretty weak to me, I'm not sure how rain would have stopped them threading some connections together.

For what it's worth, I have three tanks. Rain drains into the first one, and it is connected to the second at the top of the tank - first tank needs to be full before the second gets any. Second and third are connected at the bottom so they balance, and the pump draws from tanks two and three. In this way, I always have a reserve of 25,000l if anything happens, and it doubles as a firefighting reserve that remains full.

Yeah that's essentially how I've started managing the water, using just tank 2 and 3. I'll see what the plumber/building company says but I suspect a larger pump which is designed for more 'suction lift' is going to be the best solution. Bit of a shame, since it was all avoidable!