How Do I Know If My Hot Water Cylinder Needs Replacing?

Are you having trouble with your hot water cylinder? A common water heating system used in many New Zealand homes, hot water cylinders actually have a life expectancy of their own. Warm and hot water are a crucial part to everyday life, and while you may not always be conscious of the system that keeps your water warm, it pays to know if it needs replacing. So, how do you know if your hot water cylinder needs replacing?

How Do I Know If My Hot Water Cylinder Needs Replacing

Rusty Water?

Rusty water is a key sign to look out for. When corrosion occurs, even steel gets gradually eaten away by the rust. For hot water cylinders made from steel, this is a warning sign of potential leaking later on. So, if you find rust in the hot water coming from your faucets, shower or bathtub, it’s likely that your hot water cylinder is rusty – this is unavoidable if used past its expiration date.

Similarly, if you’re seeing rust surrounding the pressure relief valve or water inlet on the heater, odds are the inside of the cylinder has also had rust form – in this case make sure you replace your hot water cylinder as soon as you can. However, it’s important to consider if it’s a problem with your pipes instead of your hot water cylinder.

If your tap water is also coming rusty, it might just be the pipes that have the problem. Try draining several buckets worth of hot water, if the water is still coming out rusty by the time you’re on about the third bucket load – it’s definitely a problem with your hot water cylinder and time for a replacement.

Hot Enough?

If the water just isn’t becoming hot enough, it’s probably because of one of the three most frequent potential problems with your hot water cylinder:

  • Your cylinder isn’t big enough to supply your whole household with hot water
  • It has a broken heating element
  • The thermostat is incorrectly set

While the second and third problems don’t necessarily suggest a need for your hot water cylinder to be replaced as they can be simple to fix, the first problem is more likely showing that you do need a new one.

It’s possible that your household has outgrown your hot water cylinder, if more people are using it now than before, it may just not have the capacity for the size of your home. In this situation, you’re likely to need to replace your hot water cylinder with a larger one to accommodate your household’s hot water needs.

If you need some guidance as to whether to simply get a larger hot water cylinder or change your water heating system entirely, have a look here to find what will work best for your household.

Strange Noises?

Is it making strange noises? Older water heaters may have sediment building up from the strain of needing to continuously heat up more water for your home. Once sediment forms, it will harden and thicken along the bottom of the water cylinder over time causing two key damages to you water heater:

  1. It will become less efficient with its energy consumption due to the extra strain demanded when heating water.
  2. Having to spend this extra time on heating up the water, the metal of the hot water cylinder could turn brittle, this only increases the likelihood of crack formation.

Noise from a water heater due to sediment buildup tends to indicate that leakage will eventually occur if not handled properly, once your hot water cylinder starts leaking it’s a much bigger job as it may need replacing instead of just repairing. But you can somewhat stop the damage sediment causes if you act in time and follow the correct method.


When close to the end of it’s life expectancy, hot water cylinders are more at risk of leaking. Depending on where your water heater is located in your house, leakage can be dangerous and cause a lot of damage to your property, so you need to act fast once you spot signs of leakage.

Expansion to the metals within the cylinder is generally the main cause for leaks; this occurs naturally over time as the cylinder’s interior is exposed to thousands of heating cycles. To begin with, a fracture’s gap is small enough to keep the water in when the cylinder is idle but once it enters a new heating cycle, small amounts of water are able to leak through the gap when at the height of each cycle.

However, the leaking could be from alternate causes such as problems with the fittings to the tank or problems with the pressure/temperature of the outflow pipe.

If leakage is occurring in either of those parts, there could be something wrong with the fittings, the best thing to do in that case is to have a plumber come and look into the issue. If there isn’t any trace of leakage in these areas however, it’s almost definitely a problem with the cylinder, in which case it’s time for a replacement.

Too Old?

Lastly, it may just be too old. Most hot water cylinders have a life expectancy of 8 to 10 years, but can last up to 15 depending on it’s quality. It’s ideal to replace your hot water cylinder if it’s reached its expiration date even if no problems have occurred, so as to avoid any further complications down the road. You can check the manufacturer’s sticker located on the hot water cylinder to find its manufactured year.

If you have any further questions or if you want to discuss adding an excellent hot water cylinder into your home, please do not hesitate to get in touch with us at 0800 497658! Visit our store at Hot Water Solutions! We carry a wide selection of all sorts of water heaters, and we are confident that you will find one that suits your household perfectly.