Some time ago I posted about issues with my tankless water heater, concerned about the water going cold mid shower.

Recently I found the issue isn't in the water heater - there are times when all the water pressure in the house including cold and at the closest spiggot to the mail drops by around half. It seems to be pretty regular intervals, roughly every 10 minutes.

What could cause this and how can I fix it?


Thanks for the responses everyone. There is a large recycling center fairly close by. It is likely the reason for the periodic drops.

I've adjusted the regulator. Although the pressure still drops it isn't nearly as severe.

Hopefully it'll be enough to keep the flow sensor on my inline tank from kicking off.

2 Answers 2


Many homes suffer from low pressure/flow issues for various reasons. This regular drop in pressure/flow seems to indicate an external problem, such as a large water user (commercial or industrial) using water from your water main line for some automated process.

Also, check with your water distribution entity to see if they have changed the way they regulate or maintain water delivery pressures (most use pumps).

As for a fix, if one of the aforementioned causes turn out to be true, it may take some diplomatic activism (or maybe some not so diplomatic activism).


The interval is certainly suspicious and as Jimmy's answer suggests, it could be something external. You might consider asking your neighbours if they experience anything similar to determine if it's isolated to your home or not.

I would also recommend looking to see if you have a Pressure Reducing Valve (PRV) installed. They usually look something like the below image, and might be installed anywhere before or after your main meter. If you have one of these, it might need adjustment or it could be failing and require replacement.

If all else fails, a good plumber who has reviewed your plumbing setup might be in a better position to diagnose the issue.


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