Bought the house in autumn. Cold water tastes and smells clean everywhere, but every hot tap smells strongly of rotten eggs, worst first thing in the morning after the water has been sitting. Water heater is an electric tank, maybe eight years old. Do I flush it, replace something in it, or is this a well problem that only shows up in hot water for some reason?
Before the rod, try a one-off high temperature run: turn the thermostat up to 70C for a few hours, then run every hot tap for a couple of minutes each to push the hot water through the pipework, then turn it back down. That kills the bacteria in the tank and the smell often goes for months. Be careful with scalding while it's up there, especially if there are kids in the house.
Did this at the weekend and the smell is gone. Will still do the anode when I get a socket set that fits.
Worth doing anyway on a new-to-you house: drain the tank fully once and see what comes out. Eight years on a well with any sediment at all and you may get a surprising amount of sludge, which is where a lot of the bacteria live.
Whenever you get to the rod, kill the breaker and let the tank cool for a few hours first, and expect the drain valve on an eight year old heater to be plastic and brittle. I'd have a replacement brass valve on hand before you start, because discovering the old one won't reseal while the tank is half empty is a bad evening.
If it comes back within a few weeks of a flush and a rod swap, then it's worth testing the well itself for sulphate and for bacteria, because you may be continuously reseeding the tank. But start with the heater, it's cheaper and it's the answer most of the time.
One caution on the aluminium-zinc rod: some people notice a faint taste change. Doesn't bother most, bothered me slightly for a fortnight and then I stopped noticing. Powered anode avoids it if you're sensitive to that sort of thing.
Same experience. Also worth saying the powered ones need a socket near the heater, which not every utility room has.
@coopvent_cal · 2mo ago · 3 replies
Hot only means the water heater, essentially always. What's happening is sulphate reducing bacteria living in the tank reacting with the magnesium anode rod and producing hydrogen sulphide, which is your rotten egg smell. Two-part fix that has worked on three houses for me: drain and flush the tank, then swap the magnesium anode rod for an aluminium-zinc one. Some people go to a powered anode instead, which costs more and lasts far longer. Do not just remove the anode and leave it out, the tank will rust through in a couple of years.
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@coopvent_cal · 2mo ago
Handy person, but the rod is often seized in there and you'll want a breaker bar and a six point socket, plus enough headroom above the tank to pull a metre-long rod out. Segmented rods exist for tight spaces.
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@switchback_sid · 2mo ago
Is the rod swap something a reasonably handy person does, or is this a plumber job?
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