Best way to transfer water between 2 tanks?

[Oscarpop]

Part of the grand plan is to install a water maker to provide us with fresh water while we are off doing our thing.

Conventional wisdom seems to suggest not feeding the product water into the main tank.

So I think we have the space to fit a 2nd smaller tank to take the product water.

Ideally I would like a simple system to allow the transfer of water into the main tank with the minimum of hole cutting.

My thoughts initially are to have the outlet pipe from the "watermaker tank" feed directly into the top of the primary water tank with a couple of isolation valves and either a 12v water pump or a manual feed.

What do the forumites think?

Also one concern I have is what safety features I can build into both tanks in case I leave the water maker running? Ideally I need some sort of run off pipe that discharges into the bilges if the tank accidentally gets overfilled.

Ta

 

[nigelmercier]

I don't see why you can't use your normal tank.

You could just drill holes in the bottom of the sides and connect them together with a 12mm hose; the full one will partly drain into the empty one. If there is not vent, then do the same at the top.

 

[Oscarpop]

I don't see why you can't use your normal tank.

Apparently they occasionally go t*ts up and can fill the tank with salt water, which would be counter productive.

 

[KenMcCulloch]

We have a watermaker (decommissioned for the moment) and two 150L water tanks. The supply from the tanks is via a selector valve that enables water to be draw from tank 1 or tank 2. There is no other interconnection so far as I can see. The output from the watermaker goes to tank 2. In use one would keep tank 1 as reserve and draw water from tank 2. If the watermaker failed one would then have the reserve supply to eke out until either the watermaker was fixed, or another supply was reached.

 

[pvb]

Conventional wisdom seems to suggest not feeding the product water into the main tank.

So I think we have the space to fit a 2nd smaller tank to take the product water.

Ideally I would like a simple system to allow the transfer of water into the main tank with the minimum of hole cutting.

My thoughts initially are to have the outlet pipe from the "watermaker tank" feed directly into the top of the primary water tank with a couple of isolation valves and either a 12v water pump or a manual feed.

It's not a bad idea to have a second tank in case the watermaker product gets contaminated. You might be able to have a simpler system using the existing water pump. Suppose you have the outlets from the 2 tanks fed to the pump inlet via a changeover valve, then the output from the pump going to a second changeover valve (one to the normal freshwater system; the second into the filler of the primary tank). Operating both valves would pump water from the watermaker tank into the primary tank. You'd also have the flexibility to run your taps direct from the watermaker tank, if the primary tank gets compromised.

As for overflow, if the tanks are properly vented overboard, they'll just overflow overboard.

 

[Oscarpop]

It's not a bad idea to have a second tank in case the watermaker product gets contaminated. You might be able to have a simpler system using the existing water pump. Suppose you have the outlets from the 2 tanks fed to the pump inlet via a changeover valve, then the output from the pump going to a second changeover valve (one to the normal freshwater system; the second into the filler of the primary tank). Operating both valves would pump water from the watermaker tank into the primary tank. You'd also have the flexibility to run your taps direct from the watermaker tank, if the primary tank gets compromised.

As for overflow, if the tanks are properly vented overboard, they'll just overflow overboard.

clever.

thanks

 

[prv]

You might be able to have a simpler system using the existing water pump. Suppose you have the outlets from the 2 tanks fed to the pump inlet via a changeover valve, then the output from the pump going to a second changeover valve (one to the normal freshwater system; the second into the filler of the primary tank). Operating both valves would pump water from the watermaker tank into the primary tank.

Clever

If I were going on an extended cruise, though, I think I'd have two separate pumps, identical or at least similar, so that one could stand in for the other in the event of failure. (If you can get identical, you can stock fewer spares, though I'm not sure whether typical domestic water pumps have service items?)

Pete

 

[sailinglegend420]

We have three water tanks and only No1 is filled from the watermaker. When no 1 is full and the No 1 pick up valve going to the feed pump is open then water is drawn from this tank to the boat. If No2 is open as well then when No1 tank is full it overflows into No 2 via No 2 pick up valve. Same for No 3. No extra pipes or pumps are needed - just open the feed valves. KISS.

 

[Oscarpop]

We have three water tanks and only No1 is filled from the watermaker. When no 1 is full and the No 1 pick up valve going to the feed pump is open then water is drawn from this tank to the boat. If No2 is open as well then when No1 tank is full it overflows into No 2 via No 2 pick up valve. Same for No 3. No extra pipes or pumps are needed - just open the feed valves. KISS.

Can you please explain what you mean by " pick up valve"
The concept seems simple, I just can picture the valve

Thanks

 

[sailinglegend420]

Can you please explain what you mean by " pick up valve"
The concept seems simple, I just can picture the valve

Thanks

Each tank has a valve in the pick up pipe to open each tank in turn. If you open the valve on an empty tank, water from the full tank will flow back down the pickup pipe INTO the tank. Since the watermaker flow rate is slow there's no danger of overfilling the primary watermaker tank.

It was very difficult and expensive to get fittings to fill the primary tank. This way no other connections are need. I have just moved all three tank valves to a cupboard that is very easy to get at since they are used more often now.

 

[KellysEye]

Watermaker...Apparently they occasionally go t*ts up and can fill the tank with salt water, which would be counter productive.

When using our water maker we always filled plastic water containers, then tested the water, then put it in the tanks. If you are long distance sailing the last thing you need is salty water in the tanks

We have two tanks connected by a hose at the bootm of the tanks, obviously the tanks need hose fittings.

 

[prv]

When using our water maker we always filled plastic water containers, then tested the water, then put it in the tanks. If you are long distance sailing the last thing you need is salty water in the tanks

If I did that kind of sailing, I'd do the same.

In fact, I'd probably plan to carry a substantial proportion of my water supply in plastic jerrycans from the outset, eg building secure stowage for them instead of fitting any extra tankage. But contaminated or leaked-empty tanks miles from shore are a particular phobia of mine...

Pete

 

[Jamesuk]

I imagine the water maker will come with all the parts required for distrubuting the water.

We have an ENWA WM onboard and we have a valve at the control to select port or stbd tank. Surely you can do the same. We also as a back up have two separate pumps. So at the breakers board we can select stbd pump/tank which is much bigger than the port tank which also can be slected and has its own pump.

You could always put the smaller tank higher up and have a gravity feed into the larger tank. This would save power. You will need a pump to back flush the water maker system anyway after use. I would check the parts list because we use the port tank pump to back flush the system as ut must go off the product water