Connecting an additional water tank

[anniebray]

My Sadler 290 has a 150lt flexible water tank which we find inadequate. I would like to investigate fitting an additional flexible tank under the cockpit floor (ie under the bunk in the aft cabin). I would prefer to T into the existing tank outlet to pump hose which is I think 15mm & use a single 15mm hose to the new tank for the dual purpose of filling & delivery rather than have the aggravation of extending the 50mm dia hose from deck filler to existing tank. The new 15mm hose would be routed low as possible & connect to the underside of the new tank. Question is would 15mm be too small for the filling hose ?

 

[SolentPhill]

your problem may be air, 15mm is not too small as long as you dont turn a hose on too fast, but as the tank is filling the air has to come out or it will act like a balloon and you know what happens when you fill them up

 

[Tranona]

I have two tanks, the second a flexible one connected with a 50mm hose and a ball valve to isolate it. The takeoff is from the main tank, so the second is effectively a reserve supply, although I leave the valve open most of the time.

With your setup and I assume you are going for a fair size tank you would be better off having two independent tanks with their own fillers vents and take offs going to a changeover valve. You may also find it better if the shape under the bunk allows to have a custom made solid tank such as a Tek Tank.

 

[rafiki_]

There was an article on fitting an additional tank in MBM last Autumn. Can't remember which month, but you might try to contact them to confirm.

 

[Blueboatman]

I have done it the Tranona way, it works well and simply.

In fact I fitted a separate ball valve to each tank outlet ( say at the galley in an under-the-sink locker) just before they came to tee onto the galley pump.

You can buy standard drinking-water quality reinforced hose and a couple of 15mm ball valves from plumbers merchants, the diy sheds or Screwfix, or pay for silly swindlery bits..
''Theoretically'' by isolating one tank when sailing hard, you don't get water surging back and forward between the 2 tanks , which <may> otherwise squirt involuntarily out of the galley faucet each time you headbutt a wave ! You also know exactly when one tank has run dry..

I am a big fan of flexible tanks because they are so easy to clean or remove for cleaning, are quiet inexpensive and maximise the available space very well.

Of course if I were going cruising I would want both your tanks to be identical and from the same manufacturer.

Two deck filler points isn't so bad to have to deal with ( hint, second one in the cockpit and not on the side deck, so as to keep it away from salt water ingress).