The Water Supply (Water Quality) Regulations 2016

Disinfection and other treatment arrangements

26.—(1) Unless the conditions in paragraph (5) are satisfied, before supplying water for regulation 4(1) purposes, a water undertaker or combined licensee must—

(a)disinfect the water, and

(b)where necessary, subject the water to sufficient preliminary treatment to prepare it for disinfection.

(2) A water undertaker or licensed water supplier must—

(a)design, operate and maintain the disinfection process so as to keep disinfection by-products as low as possible without compromising the effectiveness of the disinfection, and

(b)verify the effectiveness of the disinfection process.

(3) Paragraph (4) applies when any property, organism or substance is present in a water source at a level that may constitute a potential danger to human health

(4) Unless the conditions in paragraph (5) are satisfied, before supplying water for regulation 4(1) purposes using water from any source, a water undertaker or combined licensee must design and continuously operate an adequate treatment process for water from the source.

(5) The conditions are that the water undertaker or combined licensee—

(a)must supply water from the treatment works as a matter of urgency in order to prevent an unexpected interruption in piped supply to consumers, and

(b)before the supply is made, has taken all necessary steps to inform consumers that the water is not disinfected or adequately treated.

(6) For the purposes of this regulation—

(a)“adequate treatment process” means a process of blending or purification treatment which removes or renders harmless the concentration or value of any property of water, or organism or substance in water, so that supplies do not constitute a potential danger to human health;

(b)“sufficient preliminary treatment” means the treatment necessary—

(i)to remove, or to reduce the concentration or value of, any property or substance which would interfere with disinfection, and

(ii)to reduce turbidity to less than 1 NTU;

(c)water is supplied for regulation 4(1) purposes when it leaves a treatment works.