Baking soda alternative that doesn't bleach?

I would like to do water only, but I have very oily hair and I’m not sure water will be enough. However I do NOT want to use baking soda on my hair as I know, over time, it lightens hair colour. Are there any good, non-bleaching alternatives to baking soda for very oily hair (not something obscure or hard to find–something I could get at a grocery store)?