The use of “chloramines” to treat water supplies has already been introduced in the Highlands to deal with concerns over the taste and smell in many homes. Last month it was rolled out to Ayrshire with plans to extend across the rest of the country.

Scottish Water insists that it is already used elsewhere UK-wide and around the world and is perfectly safe.

But Holyrood’s environment committee is to seek answers from bosses at the state-owned water giant over concerns from customers that the process, which combines chlorine and ammonia, can “produce toxic byproducts, including carcinogens.”

The use of chloramines to treat water supplies has already been introduced in the Highlands

It is less effective against bugs like EColi and Cryptosporidium, they claim, and can also kill fish in tanks and pet aquatic reptiles.

Many European nations, including France and Germany, do not use the process, along with some states in the US.

High profile US environmental campaigner Erin Brockovich has previously hit out at the use of chloramines in the Highlands, warning that adding ammonia to drinking water “does not improve it”, but instead adds chemical reactions which “are in fact more toxic”.

The issue will be raised with Scottish Water chief Douglas Millican, and other company executives, when they appear before MSPs on Holyrood’s environment committee next week.

MSPs are being urged to back independent research into the safety of chloraminated drinking water in a petition which has been lodged by Caroline Hayes.

“It has been shown that the by-products can be connected to a range of health concerns including weakening the immune system and disrupting the central nervous system.”

Her petition also calls for a review the role of the Drinking Water Quality Regulator.

Karin Craig, from Dalrymple, said she felt “blind-sided” by Scottish Water over the sudden introduction of the new process in Ayrshire.

Postcards were delivered to residents on 7 March this year warning that the new process was being introduced at the end of the month. She was later told by the firm it has already started on 19 March, meaning customers were given just 12 days notice.

“I would say that this should raise further concerns re transparency, honesty and lack of public engagement from Scottish Water,” she added. “It has put householders and businesses at a disadvantage in terms of a honest and appropriate period of notification.”

MSPs to question Scottish Water chiefs on treatment safety