Flexible Water Tank / Bladder

Does anyone have any experience with fitting a flexible water tank / bladder to their boat as a fresh water tank? I'm thinking of adding one of these to the bow of the Reefie with a 5.5GPM/70PSI ebay wash-down pump as a wash-down/rinse off solution and scrapping my plans for a seawater deckwash. I currently just use a 10ltr bucket of seawater to flood/wash off any deck blood etc and it seems to work pretty well without the seawater pressure pump reliability issues.


How well do these work/last? Can you use the full capacity of the tank once the air has been bleed out of it? Any durability issues? (Would be installed on some carpet or rubber mats)

Jackfrost80's picture

Posts: 5038

Date Joined: 07/05/12

I reckon deckwash is a must

Tue, 2017-11-14 10:46

I reckon deckwash is a must have item after installing one last year. I have a through hull strainer connected to a SS ball valve with a dual port live well pump connected to that thanks to Randall’s advice. The pump runs to a plumbed livewell tank and I have my deckwash intake running off the pump. Apart from an endless supply of water, having saltwater is also handy for filling up the esky with salt water for an ice slurry. It’s also brilliant for squirting mutton birds.

If you want the best of both worlds, big Rob H had a great suggestion when I was looking at installing my deckwash which was to install an L Port valve so that you can still run with your fresh water bladder for a freshwater washdown after a swim etc in addition to being able to use saltwater. I haven’t gotten around to this yet.


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Rob H's picture

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Date Joined: 18/01/12

Depends if you are going to

Tue, 2017-11-14 11:17

Depends if you are going to sleep aboard at all, but hard to go without salt water.

Buy your 1/2" Lport of Ebay, about $25 and pump as well, $80 or so

A final hose off with freshwater of the boat or anything for that matter dries 3 times as fast as salt water, but salt never runs out!


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Posts: 20

Date Joined: 12/08/14

Great idea

Tue, 2017-11-14 11:22

 i have a 625 Trailcraft and fitted a 50 ltr bladder from Whitworths under the floor in the unused kill tank.

Jabsco pump under the drivers seat area.

Plumbed it in with a Y piece so I can have either salt or fresh.

Salt goes to the live tank at the rear and to a hose connection for washing all the blood/ craypot bits off the boat and the freshwater goes to the same outlet on the deck for a quick shower or wash off on the way back in.

Works a treat

Darren253's picture

Posts: 352

Date Joined: 23/07/16

I already have an el cheapo

Tue, 2017-11-14 11:34

I already have an el cheapo ebay deckwash 20l/min 70PSI kit I bought about 5months ago but not plucked up the courage to cut a ¾” hole through the bottom of the hull yet! I’ve got a SS raw water pickup and seacock valve ready to go. I read so much negativity about the deckwash pumps sh*tting themselves that I thought I might give it a miss.

Option 2 would be to install a second pump (inline whale/TMC) for $25 and have the freshwater run off that. Probably would result in a much lower flowrate too eliminating wastage.

From reading, I would assume I need a second valve to protect the pump from intake pressure whilst travelling? I don’t want to be reaching into the bulge each time to operate the seacock…

We are planning on sleeping on-board but for 1-2nights rather than extended stay I would expect.

J Mann's picture

Posts: 18

Date Joined: 02/09/15

Fresh Salt Combo

Tue, 2017-11-14 13:08

I have a fresh / salt combo with a L Port valve as described above. Run it with a 50L Plastimo flexible fresh water tank and salt water intake. Good to use the fresh water for quick showers and cleaning etc when overnighting with kids but will run out if not careful. Use salt for everything else.


Go fishing they said, it's easy

gruntre69's picture

Posts: 508

Date Joined: 15/10/16

 I have two pumps, one for

Tue, 2017-11-14 13:40

 I have two pumps, one for the live well which I've connected via a timer relay module so that it runs for about 5 minutes and then off for about 5 minutes so it just continually refreshes and overflows the well. The other is for deckwash and it is connected via a 3way valve to the seacock or a bladder style 40 lt freshwater tank. I fitted a filler on the outside of the upper deck similar to the fuel filler. This valve switches the deck wash to fresh water on demand. Nice for showers on Rotto etc...

I have both pump intakes going via a second 3way valve which can either pickup from the Seacock or a second hose which is dropped into the bilge lowest point. This effectively allows me to run both these pumps to pump out the bilge along with the bilge pump in an emergency. Probably overkill but I got a bit carried away when I bought the boat...

I'm not overly happy with the bladder arrangement yet because I have it vertically mounted and I'm supporting it along the top the keep the pressure off the fill hose connection. The problem is 40Kgs in chop is heavy and I'm thinking of changing it and just letting it flop down in the cavity. Hard to explain without seeing it.

I wouldn't worry too much about cutting a hole as it s very easy to put a seacock in, however make very sure you are happy with your transducers and future placement. I'm changing my pickup now from a grated stainless scoop style to a smaller footprint resessed flange in a new location due to the installation of 3 through hull transducers..

One thing for sure is this was expensive, the fittings are all bloody pricey and this cost about $1100 to do myself.  316 hose clamps etc....

I used a very high quality double bolted clamp for onto the seacock which is below the waterline....


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Darren253's picture

Posts: 352

Date Joined: 23/07/16

Thanks for all of the input and suggestions

Wed, 2017-11-15 13:59

Cut the holes last night for the pickup/intake scoop. Will finish it off this evening...

Just ordered one of these 1/2" 12v DC solenoid valves. It's spring loaded normally closed. Going to mount it on the suction side of the deck wash pump and wire it in parallel with the deck wash switch on the dash. When switched off the valve will be closed protecting the pump from positive suction pressure. It's rated to 115PSI.


Also for phase 2 (fresh water) looking at installing a stainless L port 12v solenoid valve on the seacock discharge (after the manual ball valve) to enable me to between fresh and salt water on the dash. If I have fresh water plumbed to the NC position this this would also work as a secondary barrier to stop the seawater supply should a hose or fitting fail on the suction side.


gruntre69's picture

Posts: 508

Date Joined: 15/10/16

 I like the Lport valve but

Fri, 2017-11-17 20:08

 I like the Lport valve but it would be better if it was 316


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Cruise Control's picture

Posts: 876

Date Joined: 03/11/10

 I have 2 freshwater bladders

Sun, 2017-11-19 15:14

 I have 2 freshwater bladders on board. One for the shower and one for the sink. These are located in the port and starboard side pockets. Boat is a Cruisecraft 685 and then pockets easily accomodate the bladders which I would guess to be 50 - 75 litres. With the 75 being hooked to the shower. Also have raw water wash down. Bladders are 15 years old and the sink still has the original in line pump. Shower pump was replaced this year. So I guess longevity is not an issue.

Always use salt for washdown and this is also plumbed to the live bait tank. Can't beat showering in fresh water after a swim and the salt pump has the power to remove any fish mess from the carpets.