Step 1
Clear the water-based stained deck of all furniture and other items.
Step 2
Sweep the deck first using a large push broom. Protect the areas around your deck using large sheets of plastic. For example, any plants around the deck should be covered.
Step 3
Apply deck cleaner that's safe to use on water-based stained to the lap marks and other stains using a paint roller.
Step 4
Spread the deck cleaner using the stiff push broom. The cleaner should never be in puddles on the deck surface.
Step 5
Watch the cleaner carefully as you apply. No area should ever get dry.
Step 6
Scrub the lap marks using a stiff bristled cleaning brush. Continue scrubbing until the marks disappear.
Step 7
Rinse the cleaner from your deck within 10 minutes of applying it using your garden hose and a spray nozzle. If you think a lot of scrubbing will be needed to remove the marks, clean small areas at a time.