Noisy water pump from rainwater tank

Hello,
We've just moved into our new house. Our rainwater tanks are connected to the toilets, I've noticed when we flush it is quite noisy. The pump is not engaged every time when we flush, I think it will activate when the entire water from the pipe is used. And the noise will be there for 5-10 minutes. Our master bedroom is close to the rainwater tank, and it is really annoying during night-time.

Our pump is placed inside the water tank. Is there a way to reduce the noise or limit the intake from the tank only during the daytime.

Any help will be appreciated.

I don't find ours that noisy - but our pump is well away from living areas.

We tend not to flush during the night - unless necessary.

Our pump is well away from the u/ground tank.

Depending on time/age - maybe you should ask for a check - are you still under warranty ? Some pumps (eg German) have quite lengthy warranties). Check your papers.

That sounds like there is either a pressure tank or the mains water switching device has switched over to mains water.

You shouldn't be able to hear a submersible pump.

To limit the pump's use, you will need to turn it off during the evening so that the system switches over to mains water.

Very hard to diagnose something like this without being on site.

Thanks Saint Mike.
It is less than a year, the plumber came and had a look. He said the noise is normal.

Thank you SaveH2O


Is that (That sounds like there is either a pressure tank or the mains water switching device has switched over to mains water. ) the normal way they install the rainwater pump?

When I stand close to the tank the noise is minimal, however there is an annoying humming noise inside the house. Is it due to a faulty rainwater diverter valve?
I will request the plumber to come and have a look again, if it can't be solved I will go with a timer.

Can you please recommend someone in Sydney who is good in checking these things?

Thanks again

It's good practice to have a pressure tank when only using a pump to supply a cistern. A cistern is a slow fill (max 6 lpm), short duration end fixture and so the pump invariably is more powerful than required and it is constantly used in short bursts. A pressure tank has a reserve of water which is used first and when it is close to empty, the pump starts and fills the tank and the cistern at the same time. A 20 litre pressure tank will have a draw down of about 7 litres which will save about 2/3rd of the pump starts, but the bigger the tank, the better because there is less wear on the pump and longer durations between run times.

I'm not saying you have a pressure tank, you will have to check, but if the pump doesn't start every time, it certainly sounds like you do have one.

It is possible that the pressure tank (if you have one) has lost some pressure and the pump is cycling after the cistern has filled.

Some pump controllers do keep the pump running for a short time after the demand ceases but I can only guess as to the cause of the continuing noise from here.

You need to ask someone at a dedicated pump shop. Do you know tha pump's make and model. Any expert you ask will need to know that.

Thanks H2O for the detailed reply.
As you said, I think the plumber has installed a pressure tank.
I tried to check the make and model of the pump, unfortunately I could not as it is at the bottom of the tank and attached to a fixed pipe.

One more thing, I have noticed, even if I turn off the power to the pump some whistling noise is coming near the diversion valve intermittently

Thanks again

I would need to be onsite to see your installation to give an opinion.

Most plumbers don't have experience with rainwater harvesting systems but if you are near to a pump service centre that also does water tank installations, talking to one of their experienced guys would be the go.

Thanks H2O,
I am in Sydney ( Parramatta), could you please recommend someone, who can do an inspection and identify the issues?

Thank you Enricogala,
Building for the first time,and never thought of this issue.
I am not sure it is the issue with pump, when I stand next to the tank, there is not much noise, however inside the house it is bit more louder.

Do you think relocating the tank will be a costly exercise?

I am in Melbourne.

Given that you have a submersible pump and a pressure tank, I can only assume that the cause is due to the mains water switching device. RainBanks are notoriously inventive, do you have a Davey RainBank installed and can you hear the noise also coming from it?

Also, is the noise inside the house in the walls or is it coming from the cistern?

Does the cistern fill at a normal rate or is it slow to fill?

Thanks H2O.
The noise is coming from the wall where the rainwater connection is. the sound is much louder inside compared to outside
The cistren will fill in 2-3 minutes.
I am not sure about whether they have installed a Davey RainBank or not, all I can see( attached) photo


Thanks again

That looks like an Acquasaver that connects to the two copper pipes and to the pump supply pipe. They are a very good product that operates by the mains water hydraulic pressure. As such, it does not require electrical power.

Look it up online.

I am confident that you do not have a pressure tank. If not, then the pump should be operating every time there is a demand unless the tank is near empty. In that case, the Acquasaver will switch over to mains water.

Cisterns fill at about 6 lpm and so a 2-3 minute fill time is slow. A major but common submersible pump installation fault is when the installer simply lowers the pump onto the tank's floor where it spends its life vacuuming the floor in its near vicinity. Some submersible pumps draw water from above the floor but those that draw water from the floor should be placed on a platform that is raised above the sediment layer. I can't see any filters in the photo, it's possible that the cistern's valve stem may have a partial blockage which is causing it to slow fill and the noise from the motor is being transferred through the pipes.

I am grasping at straws here because I am not on site but you need to make sure that the pump is properly positioned if it does draw water from the bottom in any case.

If you uncouple the pipe and lift the pump to check its suction area, don't lift it by its electrical cord.

Really appreciate your help H2O.

I tried to check the pump, however it is not connected using a flexi pipe, so I was unable to lift. I can see it is sitting at the very bottom of the tank and some mud around it.
I will pass the information you have provided, to my plumber. I may request him to place the pump on a platform and install a sediment filter before the water pass through the Acquasaver valve. Do you think this will be sufficient?

Thanks again

If the pump draws water from the bottom like the one in the photo, it needs to be on a platform above the sediment layer. Unfortunately, you need to identify whether it does this otherwise raising it won't be necessary and an unnecessary cost.

If it does draw water from the bottom, the floor around the pump will be clean. If there is sediment right up to the pump, the water will be drawn from higher up unless you are looking at it shortly after it has rained and water falls into the tank at a height above the tank and near to where the pump is.

Having a filter fitted is a good idea but this is easy to do yourself or maybe ask a friend rather than pay a plumber. You could fit a wye filter on the horizontal pvc pipe between the elbow and the valve socket.

Thanks H2O for your valuable suggestions.
My plumber came and replaced and Aquasaver valve and the random noise is gone. There is some noise from the pump, but it is not that worrying.


Thanks again.

Very unusual for an Acquasaver valve to be faulty. Maybe contact the Beltrami Group and offer to send it to them so they can find the cause.

http://www.acquasaver.com.au/

My plumber told, he has installed more than hundred Acquasaver valves and this is the second one had issues with, anyway he took it back and going to claim the warranty.

Thanks again for your valuable suggestions.

Thank you plumbingdoctor,
My plumber replaced the Acquasaver valve, and the noise is gone for the time being. The tank is empty now and if the noise comes back, I will request him to check the pump.
Thanks again