What are the surfaces in your basement? If carpet or some type of fabric, the bleach will probably discolor it.
I once bought a boat that had some of the canvas heavily mildewed. I tried bleach, and it discolored the fabric but still didn't kill the mildew. What I found that worked like magic is plain old Pine-Sol in a bucket of water. Killed the mildew and did NOT discolor the fabric (really made it smell good too). Hope it works as well for you..!
Ken & Jeannie
96 Vectra Grand Tour 35' DP
Jacey (terri-poo, waiting at the rainbow bridge), Jack (silky terrier)