No sunscreen is truly waterproof, and that is why the FDA only allows three claims for water resistance. These are: 

• No claim – not water resistant
• Water Resistant 40 minutes
• Water Resistant 80 Minutes

If your sunscreen does not say either Water Resistant 40 Minutes or 80 Minutes, you should assume that it is not water resistant.

Several Brush On Block products are Water Resistant 80 Minutes. These products should be reapplied after 80 minutes of swimming and/or sweating, but need to be reapplied immediately if you towel off your skin. These products are:

• Brush On Block SPF 30 Translucent Mineral Powder Sunscreen
• Brush On Block SPF 30 Touch of Tan Mineral Powder Sunscreen
• Brush On Block SPF 50 Mineral Powder Sunscreen 
• BOB KIDS SPF 30 Brush-On Mineral Powder Sunscreen
• BOB KIDS SPF 40 Mineral Sunscreen Balm
• Quick Stick SPF 40 Mineral Sunscreen
• SOL SPF 50 Mineral Spray On Lotion
• BOB KIDS SPF 50 Mineral Sun Spray