Sabriena woke me up yesterday morning because the water heater was leaking. Huh?
I go out to have a look at it, and water is positively streaming out of copper pipe connected to the pressure relief valve. I waited until after they opened and phoned the property manager (spoke to Freya), but in the meantime we shut off the water to the entire house to stop it from wasting water (who knows how much it wasted over night).
Later on in the day we hadn't heard anything and assumed that the plumber would not be attending today, and turning the water back on to flush the toilet and so on was becoming a pain in the arse, so I found the shut-off for just the water heater and successfully isolated it.
This morning a plumber called on the phone, and I gave him the numbers off the valve so he could source an appropriate replacement. He came out just after we dropped Duncan off at school, replacement valve in hand, but upon looking at the water heater (which is quite old and dinged to shit from the previous tenants) decided he would recommend the landlord just replace the entire water heater, as apparently the valves are not cheap.
The valve has since stopped leaking, and he showed me how I can tap it gently with any sort of metal tool which will likely reseat it in the short term until the landlord decides what they're going to do. At least we can take showers today.
Update: The plumber came by this morning with a new water heater and just replaced the entire thing. We opted to not hit the boost, which means we won't have hot water today, but it probably wouldn't have been completely hot by the time we were wanting to wash the dinner dishes anyway.