I'm off to the boat in a few minutes to test my Squirrel stove after fitting it yesterday and spray painting the chimney, but the reason I am on here is I read a post where someone asked why his water pump was constantly running (that would alarm me) but there were some basic possibilities, one being the accumulator needing more air and various stuff, but someone said turn it off, do you have an on/off switch? my ears pricked up! the only switch on mine is in the engine room on the switch panel, what's the verdict from you guys? I have ordered a DC outdoor switch which I shall be fitting near to the pump, I think it is a sensible move? The picture was taken last year when I made a cupboard for the pump, so it will go into there.

22 minutes ago, Sid Charles said:

I'm off to the boat in a few minutes to test my Squirrel stove after fitting it yesterday and spray painting the chimney, but the reason I am on here is I read a post where someone asked why his water pump was constantly running (that would alarm me) but there were some basic possibilities, one being the accumulator needing more air and various stuff, but someone said turn it off, do you have an on/off switch? my ears pricked up! the only switch on mine is in the engine room on the switch panel, what's the verdict from you guys? I have ordered a DC outdoor switch which I shall be fitting near to the pump, I think it is a sensible move? The picture was taken last year when I made a cupboard for the pump, so it will go into there.

FWIW I fitted a pair of suitable domestic light switches, one in the galley and one in the toilet, so it was possible to turn the pump on and off when needed - like at night. Technically this is not best practice, but I also fitted a relay by the pump so the switches did not have to handle the full pump current. In practice the accumulator and siting the pump under the dinette meant the odd time it ran a night did not disturb unless guest were sleeping over the pump, so it did not need turning off at night, but the facility was there.

28 minutes ago, Sid Charles said:

but there were some basic possibilities, one being the accumulator needing more air and various stuff

Yes, a number of basic possibilities, but a lack of air in the accumulator is not one of them. That would allow the pump to run for sort periods while it repressurises the system more frequently, and it would make the cycling frequency greater when a tap is open. Only some kind of leak or a stuck on pressure switch would make the pump run continuously.

1 hour ago, Sid Charles said:

I'm off to the boat in a few minutes to test my Squirrel stove after fitting it yesterday and spray painting the chimney, but the reason I am on here is I read a post where someone asked why his water pump was constantly running (that would alarm me) but there were some basic possibilities, one being the accumulator needing more air and various stuff, but someone said turn it off, do you have an on/off switch? my ears pricked up! the only switch on mine is in the engine room on the switch panel, what's the verdict from you guys? I have ordered a DC outdoor switch which I shall be fitting near to the pump, I think it is a sensible move? The picture was taken last year when I made a cupboard for the pump, so it will go into there.

So long as there is nothing else on the circuit whats wrong with switching it off at the distribution board?

Even in Tony's noise nuisance avoidance scheme you don't really need another switch. I'd argue its an unnessary complication and just more to go wrong... KISS principle applies....

I have a switch on the main board, and I also fitted another between the main feed and the pump connection. I never really gave it much thought as it seemed the right thing to do. In every electrical installation I have seen it appears to be common practice to isolate the main feed near the appliance. Apart from which, if you need to work on the pump or ancillary water supply equipment, you'd soon get fed up walking back and forth the length of the boat.

6 hours ago, jonathanA said:

Even in Tony's noise nuisance avoidance scheme you don't really need another switch. I'd argue its an unnessary complication and just more to go wrong... KISS principle applies....

I agree with KISS where sensible but if having to access the main panel, which is usually at the back of the boat, involves walking through a guest's bedroom in the night then I think seeking to avoid that by a simple circuit modification is worth the extra complication. It all depends on the boat layout, how the boat is used, and personal preference.

I fell strongly that having a switch that is easily accessible and in the galley makes life that little bit easier.

8 hours ago, Sid Charles said:

I'm off to the boat in a few minutes to test my Squirrel stove after fitting it yesterday and spray painting the chimney, but the reason I am on here is I read a post where someone asked why his water pump was constantly running (that would alarm me) but there were some basic possibilities, one being the accumulator needing more air and various stuff, but someone said turn it off, do you have an on/off switch? my ears pricked up! the only switch on mine is in the engine room on the switch panel, what's the verdict from you guys? I have ordered a DC outdoor switch which I shall be fitting near to the pump, I think it is a sensible move? The picture was taken last year when I made a cupboard for the pump, so it will go into there.

I use a standard 5amp light switch

It doesn't really matter whether you use the switch from the main DC panel or fit a more conveniently located switch for your water pump. The important thing is that you switch it off when leaving the boat. Any leak while you're on the boat can be heard, but not if you're off the boat. Also, isolating the tank without switching the pump off is a very bad idea.

Edited October 4Oct 4 by blackrose

4 hours ago, blackrose said:

It doesn't really matter whether you use the switch from the main DC panel or fit a more conveniently located switch for your water pump. The important thing is that you switch it off when leaving the boat. Any leak while you're on the boat can be heard, but not if you're off the boat. Also, isolating the tank without switching the pump off is a very bad idea.

I also have an off switch for the water pump in the kitchen which I turn off when we leave the boat for any period (as well as turning off the stop cock from the tank). A recent experience however got me thinking that perhaps I should switch the water pump off even for simply leaving the boat to go shopping. When I returned to the boat this time, before going out cruising, I turned everything on, gas, electric,water and when I turned on the water the pump immediately fired up. It's not unusual for the circuit to have lost a bit of pressure, but then it just kept on running. I went into the bathroom to find that the floor was flooding. Quickly turned off the pump before investigating and found that the jubilee clip holding the water pipe for the Cassette toilet flush had randomly failed. Not a difficult job to replace, but then I thought,"What would have happened if that had failed when off the boat shopping, or in the pub for a few hours?". A water pump can discharge a lot of water inside the boat in a couple of hours and make a real mess!

9 hours ago, Wanderer Vagabond said:

I also have an off switch for the water pump in the kitchen which I turn off when we leave the boat for any period (as well as turning off the stop cock from the tank). A recent experience however got me thinking that perhaps I should switch the water pump off even for simply leaving the boat to go shopping. When I returned to the boat this time, before going out cruising, I turned everything on, gas, electric,water and when I turned on the water the pump immediately fired up. It's not unusual for the circuit to have lost a bit of pressure, but then it just kept on running. I went into the bathroom to find that the floor was flooding. Quickly turned off the pump before investigating and found that the jubilee clip holding the water pipe for the Cassette toilet flush had randomly failed. Not a difficult job to replace, but then I thought,"What would have happened if that had failed when off the boat shopping, or in the pub for a few hours?". A water pump can discharge a lot of water inside the boat in a couple of hours and make a real mess!

I tend to switch off my pump (and gas) if I'm leaving the boat for more than and hour or two, but as you say a water leak could make a lot of mess in that time. I guess it all comes down to probability and the size of the leak. As you discovered, it's important to make sure your plumbing joints are sound.

I knew a guy at Brentford 20 years ago, who wanted to connect his fresh water system direct to the mains tap at his mooring so that he didn't have to keep filling his tank. I told him that was a really bad idea because any leak would eventually sink his boat if he wasn't onboard. The worst that can happen if you leave the pump switched on and have a leak is that you'll have a tank of water in the bilges and perhaps a waterlogged floor, but at least the boat won't sink.

15 hours ago, ditchcrawler said:

I use a standard 5amp light switch

The theoretical problem with arcing damaging the contacts when a mains switch designed for AC is used to switch DC, seems to be just theoretical in practice for 12V DC. In any case, in this application, the switch would normally only be used to isolate the pump at a time when it was not running and thus drawing no current, so there would be no arcing anyway.

Except that when you switch off the pump to leave the boat for any period of time you usually open a couple of taps to release pressure in the system, at least in winter.

That means as soon as you get back to the boat and switch the pump on it will spring into life, drawing current and theoretically arcing.

1 minute ago, blackrose said:

Except that when you switch off the pump to leave the boat for any period of time you usually open a couple of taps to release pressure in the system, at least in winter.

That means as soon as you get back to the boat and switch the pump on it will spring into life, drawing current and theoretically arcing.

The arc occurs when you BREAK the contact while drawing power, 12/24V won't jump the tiny gap as the switch contacts make.

8 hours ago, Sid Charles said:

I'm off to the boat in a few minutes to test my Squirrel stove after fitting it yesterday and spray painting the chimney, but the reason I am on here is I read a post where someone asked why his water pump was constantly running (that would alarm me) but there were some basic possibilities, one being the accumulator needing more air and various stuff, but someone said turn it off, do you have an on/off switch? my ears pricked up! the only switch on mine is in the engine room on the switch panel, what's the verdict from you guys? I have ordered a DC outdoor switch which I shall be fitting near to the pump, I think it is a sensible move? The picture was taken last year when I made a cupboard for the pump, so it will go into there.

I use a standard 5amp light switch

1 hour ago, Ronaldo47 said:

The theoretical problem with arcing damaging the contacts when a mains switch designed for AC is used to switch DC, seems to be just theoretical in practice for 12V DC. In any case, in this application, the switch would normally only be used to isolate the pump at a time when it was not running and thus drawing no current, so there would be no arcing anyway.

But it's switched back on under load. They work much better than the experts say they will. My shower drain is switched at last 4 times a day when we are on board under load, it's only done 25 years

I had a pump switch failure in 2003 as a temporary measure I bypassed it. It was still like that in 2012 when I sold the boat.

The new boat didn't have a pump switch and I never noticed.

If I left the boat for any length of time I turned the CU off.

This is what I am going to use, no particular reason but they are DC and waterproof

16 minutes ago, Sid Charles said:

This is what I am going to use, no particular reason but they are DC and waterproof

We’ve got one of those on a lead for a water pump we use to drain the system. It’s probably a bit of an overkill but nothing wrong with that.

Where do you get those? I fitted a spring loaded push switch you have to hold in to empty the shower via a Gulper. I get a sore finger holding it in

10 hours ago, Peugeot 106 said:

Where do you get those? I fitted a spring loaded push switch you have to hold in to empty the shower via a Gulper. I get a sore finger holding it in

Think I got it off Amazon, I just typed in DC switch for 12volts

Kopinma IP67 Waterproof Inline Switch 12V DC 20A High Current Power Waterproof Switch As shown : Amazon.co.uk: DIY & Tools

We have a switch at the foot of the bed to turn the pump off, doesn't get used much.

On 05/10/2026 at 08:58, Tony Brooks said:

The arc occurs when you BREAK the contact while drawing power, 12/24V won't jump the tiny gap as the switch contacts make.

I'll bow to your greater electrical knowledge, but if that's true then the whole water pump switch contact arcing issue is an irrelevance, as switching off the water pump while it's drawing power isn't generally something anyone does - unless perhaps they're specifically trying to make the contacts arc!

I just use these basic DC switches. I'm not sure why you'd need waterproof switches. They seem a bit over-specified.

Edited Wednesday at 07:145 days by blackrose

7 minutes ago, blackrose said:

I'll bow to your greater electrical knowledge, but if that's true then the whole water pump switch contact arcing issue is an irrelevance, as switching off the water pump while it's drawing power isn't generally something anyone does - unless perhaps they're specifically trying to make the contacts arc!

This is true and why Brian and I have had no reliability problems from AC light switches on water pump circuits. However, on the hire fleet I could see the arc through the plastic when the switch was turned off under load, but it did not seem to affect the life or reliability.

4 minutes ago, blackrose said:

In that case the whole arcing issue is an irrelevance as switching off the pump while it's drawing power isn't generally something anyone does.

1 minute ago, Tony Brooks said:

This is true and why Brian and I have had no reliability problems from AC light switches on water pump circuits. However, on the hire fleet I could see the arc through the plastic when the switch was turned off under load, but it did not seem to affect the life or reliability.

Particularly bad for an inductive load, like a pump motor, where breaking the switch under load gives a big reverse voltage spike as the magnetic field collapses.

Also probably explains why the built in pressure switch in a water pump can be so unreliable.

When I turn ours off at the switch it is whilst the pump is running as the only time I do it is when draining the system for winter so have to turn the switch off to stop the pump once the water has run out.

1 hour ago, Sid Charles said:

Think I got it off Amazon, I just typed in DC switch for 12volts

Kopinma IP67 Waterproof Inline Switch 12V DC 20A High Current Power Waterproof Switch As shown : Amazon.co.uk: DIY & Tools

Thanks it looks ideal for where I might fit it

4 hours ago, Jen-in-Wellies said:

Particularly bad for an inductive load, like a pump motor, where breaking the switch under load gives a big reverse voltage spike as the magnetic field collapses.

Also probably explains why the built in pressure switch in a water pump can be so unreliable.

When I first started work, way back in 1972, I had to maintain and operate an old 50 volt DC switchboard, which connected the DC generators (AC motor and 600 amp.DC generators on a common shaft) to the exchange batteries.

The knife switches had sprung edges to minimize the arcing when they were opened

The image below is of similar equipment.

Edited Wednesday at 12:035 days by cuthound