Bath water not emptying through the overflow quickly enough

[McGraw]

Hi.

The overflow on our bath doesn't work properly. Water doesn't empty down it fast enough to stop the bath overflowing if forgotten about.

Our water pressure is terrible and the bath takes about 20 minutes to fill to a reasonable level. We set timers but sometimes the lad forgets and we get flooded.

The bath empties just fine through the plug hole.

I had to change the U bend a while ago and I noticed the resting water level is just below the level of the U bend. It's pretty much at floor level which means there is always water in the pipe that takes the bath water away?

Is this normal? Could it be the problem? The pressure of the bath water from the plug could be forcing the water down but the lesser weight of the water from the overflow means it doesn't empty quick enough?

I hope this makes sense.

Whatever the reason, I'd appreciate some guidance as what can be done about it.

Thanks a lot.

 

[TicklyT]

If it takes 20 minutes to fill the tub, the overflow should cope with that sort of flow rate. Overflows can get bunged up with hair and soap scum over time.

There shouldn't be any standing water in the waste pipe. The pipework should empty completely. It suggests a poorly installed waste, running uphill somewhere. Such rises and dips in the pipe run may create an airlock in the waste.

The water pressure in the waste will be the same, whether water enters from the waste or the overflow, but the higher flow rate when the plug is removed may be purging trapped air from the waste.

Aproaching your problem from the other end, are the taps installed on your bathtub suitable for your plumbing?
Brassware designed for mains-pressure installations gives a very poor performance if fitted to low pressure systems. Taps suited to low pressure systems are available, and are capable of much higher flow rates, even with very low water pressures. That could fill the tub quickly before anyone gets bored with the wait.

A temporary fix - while filling the bath, replace the plug with a piece of plastic waste pipe cut to suit the depth of your tub, so the water will overflow down that 'snorkel' before the tub overflows.
Whip the pipe out of the plughole and quickly insert the plug before bathing

 

[McGraw]

Thanks very much.

The taps are a stainless steel mixer type. They're about ten years old.

Your tip regarding the plastic pipe is great! Reckon I'll do that.

What about the long term? I know the overflow isn't blocked but I dread to think about the work involved to sort the pipes out.

Cheers again.