Recently I bought ingredients to brew my first all-grain IPA, and realized that my boil kettle isn't wide enough to steep all the grains in one muslin bag so I came up with the following idea.

1) split the grains (10.5lbs two-row and 1.25lbs specialty grains) into two bags (one muslin and one nylon) and steep one on top of the other.

2) to sparge I'd put a strainer (colander) on tap of my brew kettle and pour 170F over the bags (one at a time) until I reach 5 gallons.

My questions are the following:

1) is this a good idea? 2) how much water do I need to steep the grains in?

Sorry this post may be too late, but it looks like you are trying to brew an all grain IPA. Steeping your grain by pouring 170 degree water through grain bags won't work very well.

My all grain brewing includes two maybe three batch sparges (15 minutes each) at 170 degrees (excluding the original mash for 60 minutes at 152 degrees).

Good luck and have fun.

Randy

Let us know how it came out.
I batch sparge just 1 time after mashing for an hour.
Sounds like it will work, not the most efficint way but should make beer.