A smart water meter logs every litre in fifteen minute blocks. Between tenancies the flat uses nothing for weeks and then, on one night, a hundred and ninety litres at the flow rate of a bath tap.
I own a ground floor flat in a converted terrace and I let it out, and I am going to be boring about plumbing for a while because it is the only way this means anything.
The flat has its own water meter. Not a shared supply with an apportionment, which is what most conversions have and which would make everything below meaningless. It has its own, in its own pit in the pavement outside, on its own service pipe, installed in 2016 when the conversion was done, and the water company will confirm that because I have asked them to three times.
It is a smart meter. It records consumption in fifteen minute blocks and sends it once a day, and I can see those blocks on the water company's portal going back two years, and I have downloaded them every month since 2019 so I have the lot.
The only other thing you need is that there is one stopcock, inside, under the kitchen sink, and turning it off stops all water to the flat.
Between tenancies I turn that stopcock off. Always, because a burst pipe in an empty flat is the thing that takes a property off the market for a year.
With the stopcock off the meter reads nothing. That is not an assumption, it is four years of fifteen minute blocks with zeroes in them, and the zeroes are what makes the other nights visible.
Once or twice in every void period, there is a night with water on it.
Here is what one looks like, and I am reading from the February before last because it is the clearest.
Nothing at all for nine days. Then:
04:00 to 04:15, sixty two litres. 04:15 to 04:30, eighty one litres. 04:30 to 04:45, forty seven litres. 04:45 onwards, nothing, for the rest of the void.
A hundred and ninety litres in forty five minutes.
That number is not an odd number and that is the thing that has kept me up.
A standard UK bath holds about a hundred and eighty litres filled to a normal level. A bath tap runs at between ten and eighteen litres a minute depending on your pressure, and mine is on the better side of that.
A hundred and ninety litres over forty five minutes, fastest in the middle, tapering at the end, is a bath being run slowly and topped up.
It is not a burst. A burst does not stop. A burst is a flat line that goes on until somebody turns it off, and the water company's system alarms on exactly that pattern and has never alarmed on mine.
It is not a leak. A leak is small and constant and shows in every block, all night, every night.
It is a tap being opened and then closed.
What I have done, in order, over four years, and some of it I am not proud of.
Checked the stopcock. Every single time, before and after. Off. I photograph it now, with the date on the phone, going in and coming out. I have forty one pairs of photographs of a stopcock.
Had the meter tested. The water company will do it, and they did, and it was found accurate, and I paid for that too.
Checked whether the meter is mine. Three times, as I said. The third time an engineer came out, lifted the pit, and we turned my stopcock on and I ran the kitchen tap while he watched the meter, and it turned, and we turned it off and it stopped, and he signed a bit of paper saying the meter serves my property.
Changed the locks. Twice. The second time to a lock that logs, and the log is empty on those nights, and the windows are sealed units with keyed restrictors on the inside.
Asked the upstairs flat. They have their own meter and their own stopcock and they are a retired couple who have lived there eleven years and who go to bed at ten. I have seen their bills, which they showed me unprompted because they thought I was asking about a leak affecting them.
The bathroom, because eventually you have to go and look at the bathroom.
The bath is a standard steel bath, boxed in, fitted in 2016 by the developer. The taps are a mixer. There is no shower over it, just a handset on a hose.
On the morning after, three separate times, I have gone in before the cleaner.
Twice there was nothing. The bath was dry, the plughole was dry, the taps were dry, the window was shut. A dry empty bathroom in a cold flat.
The third time the bath was wet.
Not full. Not damp with condensation, which I know the difference of, because a cold bath in a cold flat does go damp and it looks like dew and it is all over everything. This was a wet bath: water standing in the bottom in the dip by the plug, maybe a cupful, and a tide line of wet enamel about a third of the way up with the dry above it, and the hose of the handset lying in it.
The taps were dry. I checked that and then I checked it again.
What I told myself, for about a year, was that one of three contractors had been in. I have given keys to a plumber, a decorator and a man who does the boiler service, and I rang all three about specific dates, and all three said no, and two of them said it with the tone of a man who has been accused of something.
What ended that theory is the hundred and ninety litres.
A contractor does not run a bath. A contractor runs a tap for twenty seconds to see if it runs. The boiler man bleeds a radiator, which is a litre. None of them has any reason to put a hundred and eighty litres of water into a bath in a flat nobody lives in, at four in the morning, and then pull the plug.
The water goes out. That is the part that finishes it, and I only realised it in the second year.
Whatever came out of that tap went down the waste, into the soil stack, and away, because the flat has not flooded and the ceiling downstairs is a concrete slab and there is no downstairs anyway. The meter says a hundred and ninety litres came in and the flat is dry, so a hundred and ninety litres left.
Somewhere in the street, at about half four in the morning, a sewer took a bath's worth of water out of an empty flat, and there is nothing in that chain of events I can point at and call a fault.
I am still letting it, and I will keep letting it, because I have a mortgage on it and the yield is the reason I have a pension at all.
What has changed is small and it is the only thing I have that works.
I leave the immersion on. The flat has a small electric water heater in the kitchen cupboard for the hot side and I used to turn it off at the isolator with everything else, and for the last eighteen months I have left it on, which costs me about four pounds a week in a void.
In the eighteen months since I started doing that there have been eleven void nights with water on the meter, which is the same rate as before.
But the bath is wet every time now, and the tide line is high, and twice the flat has been warm when I have come in at eight with the heating off, warm the way a bathroom is warm after somebody has had a bath in it with the door open, and I stood in my own hallway both times and said good morning out loud before I could stop myself.