Adding water after fermentation has started

[mattpocket]

I've brewed a kit a tad too short and need to add an extra couple of litres. Can I just use tap water or should I use bottled to prevent introducing any nasties? The water that went in at the start was untreated tap water.

[oldtom]

For what it`s worth I always treat my water with half a campden tablet in 5 gallons then top the FV up to the required level. If it`s just a couple of lts then maybe try boiling it and letting it cool before adding. IMO it`s worth using the campden tablet to treat tap water as it gets rid of the chlorine and chloramates from the water. My beers have been a lot better since I picked this simple tip from the forum.

Paul.