Top 5 Reasons Your Water Tank Is Leaking
A leaking water tank can be a worry, whether it’s water damage in a vehicle or a tank that keeps running dry. The good news is that leaks in plastic water tanks usually come down to a small number of causes, and most are easy to fix.
The 5 most common causes
- Not enough PTFE tape on the fittings
- The wrong fittings
- A leaking lid
- Physical damage
- An overtightened tap
This list isn’t exhaustive, but it covers the reasons we see most often. Before you start, dry the outside of the tank, fill it, and watch where the water first appears: a piece of dry kitchen roll held against each fitting is a quick way to find a slow drip.
1Not enough PTFE tape on the fittings
Threads on their own don’t make a watertight seal: the PTFE tape does. If a tap or fitting was fitted with too little tape, or none at all, water can creep along the threads and drip from the outlet.
The fix: remove the fitting, clean the threads, and rewrap with at least 9 wraps of PTFE tape before refitting. Our step-by-step tap installation guide shows how.
2The wrong fittings
If a fitting isn’t the same size or thread type as the outlet, it may screw in part of the way and feel tight, but it will never seal properly. Forcing it can also damage the outlet threads.
The fix: check your outlet size and whether the thread is male or female, then use fittings made for it. Our outlet size guide walks you through it, and our fittings by outlet size make it easy to find a match.
3A leaking lid
If water appears around the top of the tank, the lid is the usual suspect. Seals and gaskets wear over time, and a lid that isn’t seated properly will let water out, especially in a vehicle where the water moves around.
The fix: check the lid is screwed down evenly and the seal is in place and undamaged. Replacement lids, gaskets and seals are available for most tanks.
4Physical damage
Knocks, rubbing against a vehicle body, or long-term movement can damage a tank or its fittings. In cold weather, water left in taps, fittings and pipework can freeze and split them.
The fix: look closely for cracks, especially around outlets and fixing points. Damaged fittings can usually be replaced, but a crack in the tank itself normally means a replacement tank. If you’re not sure, send us a photo and we’ll advise.
5An overtightened tap
It’s tempting to give a tap an extra turn to stop a drip, but overtightening is one of the most common causes of cracked outlets on plastic tanks. Once a plastic thread is damaged, it won’t seal however tight it’s done up.
The fix: taps and fittings should be hand-tight only, with PTFE tape doing the sealing. Read our note on avoiding cracked water tanks.
Find fittings to suit your tank’s outlet size.
Still leaking?
Send us a photo of where the water is coming from, along with the tank model, and we’ll help you work out the cause.
Call 01308 479960 or get in touch online.