The first time I noticed it properly was around two in the morning.

I’d woken up for no obvious reason, the sort of half-awake moment where the house feels unusually quiet. Then I heard it. A low rushing sound somewhere outside, followed by a steady glugging noise that went on for several minutes.

At first I assumed something had broken.

When you live in a half-finished house, strange sounds at night usually mean one thing. Something else needs fixing.

I got up, walked through the hallway, and opened the back door onto the terrace. The air had that slightly dusty inland Valencia smell you get after a warm day. Somewhere in the distance a dog barked once and then stopped.

And there it was again.

Water moving.

The tank filling.

It turned out nothing was broken at all. The system had simply kicked in overnight when the pressure was right. The house was quietly topping up its water storage.

I stood there for a few minutes listening to it, slightly amused at myself for assuming disaster.

Back in the UK water was something that arrived invisibly through pipes and was rarely thought about again. Turn the tap, water appears. Flush the toilet, it disappears. The system works and no one really notices.

Here it’s different.

The house stores water. It thinks about water. It waits for water.

Which means, slowly, we’ve started thinking about it too.

The kids noticed it before I did, actually. One afternoon a few weeks ago my youngest asked why the water tank was “bigger than the car”. It does look slightly ridiculous sitting beside the house, a giant plastic reminder that we live somewhere much drier than where we came from.

Now it’s become part of family life in the strange way these things do.

My wife reminds everyone not to leave taps running when brushing teeth. The twins have turned checking the tank level into a kind of unofficial game. And I’ve found myself doing something I never did in Britain, which is looking up at the sky and wondering when it might actually rain.

It doesn’t feel like some grand environmental gesture. No one here is walking around talking about water sustainability.

It’s just practical.

When water is stored rather than endlessly supplied, you notice how quickly it disappears. A long shower suddenly feels different. Washing the terrace suddenly feels wasteful. Even watering the plants becomes a small calculation.

None of this is dramatic. No one is rationing anything.

But the awareness creeps in quietly.

Sometimes it arrives at two in the morning when you hear the tank filling again. That slow, steady sound of something valuable being stored for later.

The house breathing, in its own slightly mechanical way.

And standing there on the terrace in the dark, listening to it, I realised something that probably should have been obvious earlier.

Sustainability rarely arrives through big decisions.

Most of the time it arrives through small noises you start paying attention to.