Households lost supply on Saturday night after Pembury Water Treatment Works had stopped working “due to a bad chemical batch”, South East Water (SEW) said.
Tunbridge Wells MP, Mike Martin, called for the resignation of the SEW boss David Hinton, labelling the situation “a total failure of leadership”.
He said on Tuesday: “It has been challenging. Every time they seem to get it wrong.”
In response, Matthew Dean, from SEW, said: “Our focus is entirely on returning supplies to our customers as soon as possible.
“Once we have returned supplies to all customers, a thorough investigation will take place into what happened.”
Bottled water stations in Tunbridge Wells have reopened at three locations – Tunbridge Wells Sports Centre, St John’s Rd, Odeon Cinema, Knights Way and RCP Parking.