Hi Tangerine9,

It looks like you haven't had a response so maybe we can help you out. Not sure if you are still having an issue but here is what we recommend before you call a plumber:

1. Before going to bed tonight switch off your toilet cisterns at the isolation valves.
2. Check all that all taps are turned off and there are no leaks.
3. Advise the family to not use any water overnight. Make sure no appliances/sprinklers etc. are using water.
4. Now go out to your water meter and write down the reading displayed on the meter.
5. The following morning before any water is used go back out to the meter and check the reading again.

If the reading has changed overnight then this would indicate that there is a possible leak on the water line that may be causing you to have a consistent wet patch.

If the reading did not change then you are likely to have a sub soil water issue. For both issues you are still going to need a plumber to help you out, but this will at least let you know what they should be looking for.

For standing water more often than not an agricultural/soakage drain needs to be installed to take the water and any other sub surface water through to the storm water drains.

Hopefully this helps you out!

Kindest Regards,

The Plumbing & Electrical Doctor.