Plastic water tank repair

[Sailfree]

I appear to have a leak in the boat plastic water tank.

Is it possible to do a quality repair or get it done professionally?

 

[Norman_E]

A lot depends on what particular plastic it was made out of. Some can only be joined properly by welding. I suggest that you first try to find the actual leak, for example is it from a crack in the plastic or from a failed or badly made joint, or from a fitting. If it is the latter you are in luck because fittings can be replaced or re-sealed to the tank quite easily. If it is the tank itself you will probably have to take it out to get it fixed and may need professional help.

 

[NormanS]

I have a small split near the neck of the fuel tank on my little Mariner outboard. It only shows when I lay it down in the boot of the car. :disgust:
I have high hopes of welding it with a piece of similar material and a soldering bolt. Yes, I'll make sure it's free from petrol first.
With your water tank, it depends mainly on accessibly. Give it a go. What have you to lose?

 

[macd]

As said, the type of plastic is key. The tank should have a moulded identifier somewhere (its main purpose to identify the plastic for recycling). Wiki, or legion other web pages, will help you decode this.

Suitable plastic welding rods are freely available, although you'd be wise to do a few practice runs on gash materials first.

 

[Ian_Edwards]

I successfully repaired a Vetus plastic fuel tank, using a temperature controlled soldering iron and plastic welding rods brought from ebay.

I filled in screw holes made by self tapping screws and patched a cutout, originally for a fuel gauge sender, with a bit of plastic chopping board bought from the local Tesco. I cut the chopping board so that the patch was slightly bigger than the hole and then whittled the edges with a sharp knife so that it wedged neatly into the hole. I then ran a hot soldering iron around the joint adding filler rod where necessary.

I practiced a bit on the chopping board to get the correct temperature for the soldering iron, but once I got that sorted it was remarkably easy to make a diesel proof repair.

 

[macd]

I successfully repaired a Vetus plastic fuel tank, using a temperature controlled soldering iron and plastic welding rods brought from ebay...with a bit of plastic chopping board bought from the local Tesco.

The chopping board was probably HDPE. This can be welded to itself or, with some limitations, to LDPE. Fine if the OP's tank is either, but it may not be.

But delighted your job was a success.

 

[penberth3]

...I have high hopes of welding it with a piece of similar material and a soldering bolt. Yes, I'll make sure it's free from petrol first.
With your water tank, it depends mainly on accessibly. Give it a go. What have you to lose?

I've bodged a few plastic repairs to HDPE with a soldering iron. Don't ruin the soldering tip, make something - if the tip's held in with a grub screw a 4" round nail is a good start, cut the nail down to a suitable length. You can smooth off or shape the head with a file if necessary.

Milk bottles are a suitable source of HDPE - the recycling symbol tells you the type of plastic.

 

[Capt. Clueless]

Milk bottles are a suitable source of HDPE - the recycling symbol tells you the type of plastic.

I was going to suggest that myself, having watched a you tube video using a plastic milk carton to repair a plastic dinghy.

 

[Dull Spark]

I was successful once in repairing the cracked plastic header on a car heater, where the pope connected to it. I prepped the area, washed it with solvent and then packed it with Milliput, which as I recall, advertised itself as being capable of hardening under water. There was no further leakage. I don't know what type of plastic it was.

 

[VicMallows]

I've successfully repaired a caravan 'aquaroll' water tank using one of the modern hybrid-polymer adhesives (such as 'stixall') used as a surface mastic about 3mm thick. Obviously abrade/clean the area thoroughly first. It took about a week to fully cure before use.