top of page

Why Is My Water Tank Leaking? - Core List of Reasons





For those who oversee or own a cold water storage tank, coming across a leak can be a painful and potentially expensive experience. Whether it's a steel tank, GRP tank or concrete tank, all variations of water tanks are susceptible to leakages over time and often require a specialist contractor to identify the primary cause, in order to propose the most optimal solution. Whether it's a minor leak or a major flood, we'd always recommend turning off the tanks supply to limit any additional damage from occurring, typically this is performed via the shut-off valve on the inlet. Once drained, locating and appraising the damage will be a much more seamless process. So, what are the main causes of water tank leaks? Some may be the result of a poor maintenance schedule; some may be the result of an old system age. Ultimately, we feel it's important for those responsible to develop a broader understanding of the how's and why's when it comes to cold water tanks.


  • A corroded internal substrate - This is common with water tanks reaching the end of their natural lifespan, with steel tanks being particularly susceptible. You should always ensure your tanks internal surfaces are treated with a protective coating to prevent corrosion from occurring quickly.

  • Breakdown of the mastic sealant - With the likes of sectional panel tanks, mastic sealants can fail to bond and peel off. This is often connected with overt mould developing or an improper application, causing water to flow out.

  • A faulty flow-control valve - If your water tank is leaking from the overflow, then it's more than likely that your float operating valve is in need of repair or replacement.

  • Cracks in the connected pipework - Typically, damage to cold water tank pipes is stimulated from exposure to cold weather, highlighting the importance of applying insulation to these components. In addition, general wear and tear can sometimes be the cause of tank pipe leakages.

  • Hairline fractures - When it comes to plastic water tanks, this can often be frequently occurring issue. These gaps can be formed through the natural deterioration of the tanks material, with issues escalating further if not identified early on.

  • Sudden pressure changes / structural movement - A poorly installed and unmaintained system may succumb to overwhelming strain in the event of high or fluctuating water pressures, resulting in leaks to form. When your water tank is being constructed, the extent of the system it will be serving must be considered.

  • Structural Defects - A commonality with water tanks assembled through poor design or installation. These defects may only become apparent after the system is live.

  • Non-WRAS Approved Materials - If your water storage tank has been set up using connectors and valves that haven't been approved by the Water Regulations Approval Scheme, there's a high probability that over time leaks will appear from these areas.


Do You Have a Leaking Water Tank? We're here to help!


Tank Reline are armed with over 50 years of water management experience to manage and resolve all water tank leaks, across UK commercial sectors. With 5 project hubs based throughout the United Kingdom, we pride ourselves on our nationwide responsiveness to any enquiry, saving you both time and money. As members of the Legionella Control Association, CHAS, SafeContractor, Constructionline Gold and ISO 9001, we lead the way in quality and serve some of the globes most established Facilities Management organisations. If you're in need of a trusted contractor who will place your exact needs at the forefront of its operations, then get in touch today. Click here to learn more about our leak prevention services.




704 views
bottom of page