A customer that wishes to switch supplier to a water supply licensee must satisfy each of the following three requirements:

• The customer's premises are not household premises
• The annual consumption of water on the premises must not be less than 5 million litres at the time the customer wishes to switch
• The premises are not being supplied by another licensee, but may be supplied by a licensee and one or more appointed water companies

In all cases, it is the licensee rather than the water company that must make sure that the premises of a potential customer are eligible to switch supplier. Licensees can only supply customers at individual eligible premises. Each of the premises supplied must be eligible by itself. A customer cannot aggregate consumption at more than one set of premises in order to be eligible, although some groups of properties may constitute a single set of premises in certain circumstances. There will be a single set of premises in any the following circumstances.

• The premises are located within a single boundary and a single customer occupies the premises and is liable for water bills for those premises.
• The premises consist of 'co-located' buildings (or land) which have adjoining boundaries or which are separated only by transport infrastructure, and a single customer occupies the premises and is liable for the water bills for those premises.
• The premises consist of a single building or co-located, separately occupied buildings, with all of the following characteristics:
1. they have a common landlord or managing agent
2. they have adjoining boundaries or are separated only by transport infrastructure
3. they are served by a self-contained common water supply system that does not belong to the water company
4. a single customer is liable for water bills in respect of the totality of the premises.

Premises that are considered to be a single set of premises must also satisfy the requirement that they are not household premises. For the purposes of water supply licensing, household premises are those in which, or in any part of which, a person has their home and where the principal use of the premises is as a home.

Our guidance provides more detail about how eligibility should be assessed.