In some cases pressure problems are caused by the customer's own pipework. For example a damaged or leaking pipe or a partially closed internal stop tap. In other cases, customers' pipes are old and have become corroded, restricting the water flow. In these cases the water company is not responsible for solving the problem. Pressure can also be affected by the height of a customer's property, i.e. properties at the top of a hill may receive lower pressure than properties which are at the bottom of the hill.
Pressure varies during the day depending on the demand for water placed on the supply system.
There can also be problems during dry spells when people are using sprinklers and hosepipes to water their gardens. Companies are required to supply water constantly and at a pressure which will reach the upper floors of houses. Ofwat requires companies to report annually on their performance. This is measured against a standard set by Ofwat. This measures the number of properties at risk of experiencing water pressure below the standard.