01 Sept 2026
Your water heater has failed, somebody has told you it can be repaired, and you are working out whether that is money well spent or money spent twice. The repair is cheaper today and the replacement is cheaper across the next few years, and nobody can say which side of that line you are on without a few specifics.
If you have not established what is wrong yet, start with our post on what to check when there is no hot water: several common causes are not the heater at all.
The one case that decides itself
If water is coming from the body of the tank, the decision is made. A tank that has corroded through cannot be repaired, and no sealant gives you back a vessel you can trust under pressure.
The distinction to draw is where the water leaves. Water at a fitting, a valve or a connection is repairable and often minor. Water weeping from the shell itself, or arriving from underneath while every connection is dry, is the end of it. A dripping pressure relief valve is its own conversation: it can be the valve, or the valve doing its job because something else is wrong.
Six questions that settle the rest
Is the part still available? This quietly decides a great many cases. Elements, thermostats and control boards for a discontinued model can be hard to source, and a repair that depends on a part nobody stocks is not really a repair.
Is this the first fault, or the third? One failure on an otherwise sound unit is a repair and an easy call. A second or third in a short span is different: you are buying a replacement in instalments and getting none of the benefit. Count the visits honestly.
How old is it? Manufacturers publish an expected service life for their units, measured in years rather than decades. Look yours up rather than guessing. A heater comfortably inside that span with one clear fault is usually worth repairing. One at or past it is a replacement that has not happened yet.
Where is it mounted, and how would it fail? A storage tank in the ceiling recess above your bathroom fails downwards, into your ceiling and sometimes into the home below, and by then the water has been going a while. An instant heater on an open wall fails where you are standing. Nursing an old unit along is a fair gamble in the second case, a poor one in the first.
Is the installation part of the problem? If the heater is undersized for the way your household uses hot water, if there is no isolation valve so every service means draining a whole run, or if it sits where nobody can reach it, a repair puts you back where you started. Somebody is opening it up anyway, so that is the moment to correct it.
What is happening in the next year? Replacing a heater a few months before you redo the bathroom is money spent twice, and repairing one you are about to take out is money spent well. Timing is a legitimate part of this, and usually ignored.
Get both prices in the same conversation
Refuse to consider the options separately. On the same visit, ask for the cost of the repair and of a like-for-like replacement, and set the two figures side by side with the age of the unit in mind.
The judgement is not arithmetic, and anyone offering you a tidy percentage rule has invented it. You are weighing a smaller sum for an uncertain amount of remaining life against a larger sum that resets the clock and brings the manufacturer's warranty with it. A modest repair on a young heater is a repair. A serious fraction of a new unit on an old one is a replacement.
What replacing actually involves
So the figure makes sense: draining and removing the old unit, checking the mounting will carry a full tank, making the water connections, fitting an isolation valve so the next service is simpler, and leak-testing before handover.
Two things people are often not told upfront. The electrical connection is separate work and must be carried out by a Licensed Electrical Worker, a different trade and qualification from plumbing, so that half is arranged and quoted separately. And changing type is not a straight swap: moving from a storage tank to an instant unit, or the other way, changes where it sits, the pipework and the supply behind it.
If you have decided to replace and are choosing, our post comparing instant and storage water heaters covers that. Our water heater installation work covers supply as well as fitting, and the pricing page shows where common jobs start. An on-site survey starts from $30 and covers the trip and the diagnosis.
When to call a plumber
Call when you have a fault you cannot explain, when the same unit has failed more than once, or when you want both figures in front of you before committing. Call straight away, and leave the heater off, if water is coming from the unit itself, if it trips the breaker repeatedly, or if it has started making noises or smells it never made before.