better to use tap or grocery store water for full boil ?

Doing 5 gallon extract batches. Have used both.

Would distilled water be better?

I don't use my tapwater unless I remember to draw it and let it sit for 24 hours to let clorine evaporate. I have a neighbor that has really good water that I get sometimes. have to use an old time hand pump to get that water. and sometimes I just buy water at the store. and distilled is fine with extract

Tap water is fine for full boil. Any chemical contaminants such as chlorine will be boiled off within 10 minutes and microbes shouldn't be any longer than that. For top off water, either use store bought water, filtered water or pre-boil some water(if you think you need 2 gallons, boil 3) and store it in a sanitized container.

I am pretty sure that cloromines do not boil off and contribute off flavors. BUt that is my tapwater and I choose not to use it for peace of mind.

Thanks I will stick with store bought

Chloramines don't boil off easily. When we were doing extract and partial mashes we got the 5 gallon jugs and filled them up at the store. It's quite a bit cheaper. After a while we just bought a basic filter and have been happy with the results as well.

Thanks I will stick with store bought

If your water tastes ok use tap water if using extract. Using distilled water can be ok with extract but if mini mashing you will run into problems because of the lack of ANYTHING in the water to convert sugars.

I use half and half with dark beer and 4 to 1 distilled water but ass calcium chloride and 1% sourmalt to lower the ph.

If your are really getting into it get a water report from Ward labs to see what you have in your water.

Yup, the main issue is the chloramines. As far as a homebrewer is concerned, they basically can't be removed by techniques that work for chlorine (i.e. carbon filtering, boiling, evaporation, etc.). You can force it to sediment out with use of campden tablets and then siphon your clean water out to use, but I prefer to add as few "foreign" elements as possible to my beers. I try to use campden tabs only when I'm sterilizing a fruit must (even then, I try to use high-proof alcohol to sterilize when additions are small).

The city water here is variable - with a natural water source, they have to alter their additions seasonally, so I don't want to be hassled with calling every time I brew and just buy a consistent brand of spring water (had a solid water report and has given me good results thus far).

Unless you're getting ready to start messing with adjusting your water chemistry with salts and acids, skip the RO water. Depending on the quality of the company filtering it, RO water should have pretty much everything stripped out of it. Including all of the trace minerals and elements that are needed in the various steps of the brewing process. RO water is usually used in brewing for two reasons: #1 - to dilute brewing waters that are too high in a particular salt or adjust pH; and #2 - to start with a clean water profile and manually add ALL elements and ions desired (quite an advanced brewing technique with a lot of cross-factors)

I only use tap water, no boiling the top off or anything. However, we have notoriously good tap water in NY and long island and I have a mass filter in the basement and a second filter at the faucet. Haven't had a batch yet with off flavors