My (landlord's) house has a two tank system where one tank collects rain water, tops up a secondary tank and is filtered before coming into the house.

I got back this evening and both tanks which were full 24 hours ago are empty. There's no water coming from any taps etc in the house and the mains water is trying to fill the empty tanks.

I've looked around the property and can't see where a) any taps have been on any obvious signs of a broken pipe somewhere.

Any suggestions as to what might be the problem and what I can do?

Thanks a lot,

Mike

Do you also have a pump? And has that been running? Depending on your 'valve system', you may have dumped the water from your tanks to the mains. (?) If you have a leak somewhere that should be obvious.

I do have a pump but no idea if it's been running. It wasn't when we got home.

I can't see a leak anywhere. I've spoken to the landlord who's arranged for a plumber to come in the morning. I turned off the water supply outside of the front gate so at least the tank isn't trying to fill itself. What confused me was that when the mains water was trying to fill the tank, it wasn't / couldn't but I also couldn't see where the water was going.

The son had a bottled water shower and I'll go into work early in the morning and have a quick swim. As long as it doesn't last more than tomorrow, it's not the end of the world.

With no water to pump the pump itself had likely overheated and failed for that reason. You really should have turned it off. Expect you will find a broken pipe or tap when pump has water to provide pressure - could be a toilet and not easy to see but likely obvious if two tanks of water lost while being fed.