Washing machine has started to moan intermittently at the end of the fill cycle (noise lasts about 3 - 4 seconds).
Prior to the washing machine the 2 toilets started intermittent moan on refill cycle - only one or the other, never both on same day. Understand the toilet problem relates to the ball cock valve however the new washing machine noise raises confusion.
What could be causing that noise?
Thanks

Does your system have a pressure reducing valve on it?

No pressure reducing valve is involved.
Thanks

[giggles] I may need a nap. Maybe your washing machine is tired.

[ OK, straight face now] I am guessing because I am not sure of what you mean by a 'moan'. I would try turning the stops off on the toilet and filling the washing machine and see if it still makes the noise. Are the valves to the washing machine fully open? When the toilet makes the noise does the water in the tank look like it is vibrating?

Thanks all. Sound more correctly a 'hum'.
But divine intervention today - 30 Jan.
Hum has suddenly disappeared completely as of +/- noon. No corrective action had been attempted.
Like a cyber mystery.:D