The Other Half was filling the sink to wash the dishes this evening when the water ran out.
I checked the loft header tank. It was empty. The main header tank on the hill was half full—about 7,000 litres of water.
I checked the flow at the stop cock where the water enters the house. It was good, so the pipe wasn’t frozen.
I methodically worked my way through all the sections of pipe leading up to the loft header tank: water was passing through both filters, water was passing through the stop cock after the filters, and water was reaching the stop cock in the loft.
However, no water was flowing from the ball cock in the header tank. I dismantled the valve. It was in good condition and no water flowed when it was removed. I re-assembled the valve.
I removed the section of pipe between the loft stop cock and the ball cock. It was clear. I turned the loft stop cock on and water flowed.
After re-attaching the pipe to the stop cock but not the ball cock, I turn the stop cock on and water flowed but only halfway up the pipe.
It appears we don’t have enough pressure to push the water through the filters and into the loft header tank. The bottom of the hill tank is about 20 metres above the top of the loft tank, which has provided sufficient head to push the water through the pipes in the past but doesn’t appear to be enough with the extra pipework.
To complicate things further, we need water to run the central heating. And the sub-zero temperatures mean our 2,000 litres of reserve rainwater is frozen solid in its tanks.
I’m now running the borehole pump continuously to see if filling the hill tank to the brim makes a difference. Fingers crossed!