Problems at Arkley Reservoir in orehamwood have caused some ppeople in North London to be without water. This is all due to a faulty valve. It is being fixed, however bypassing the problem could take several hours. Once water is restored, customers might see a change in the appearance of their water. It might be cloudy and discolored. Customers can still use it since it is not harmful.

London homes left without water due to faulty valve – BBC News