UK - Daily Echo - Agreement threat

Agreement threat
THROUGHOUT my life living in Southampton, I have used, and still use a water supply of the purest quality, historically supplied by various suppliers; the latest being Southern Water.
I consider that after 66 years of life, a time honoured agreement has become established between myself and the water companies, to supply a quality of water that fulfils my expectations, and as a result forms what is nowadays referred to as a Service Level Agreement (SLA), where I happily pay for a quality of supply that conforms to the status quo.
Should my water supplier consider me altering this time honoured standard, as a direct result of pressure from a third party, to add chemicals to my water supply so as to remedy any perceivable dietary or other health concerns within minority groups -without the water supplier seeking my permission to do so - then I would regard this as absurd, and consider the Time Honoured Service Level Agreement broken -by my supplier.
We only have one delivery network, and one supplier. Southern Water, must be made aware that any chemical changes to the water supplied to 200,000 of us, their local customers, will lead to refusals to accept changes within the established agreement. J W E POPE, Woodmill, Southampton.