As long as your cans are sealed properly ( body gasket in the correct place and the ring tight- I have seen a number of DH regs with the gasket on the wrong side) and there are no cuts in the hoses (common near the edge of the horn) then water is coming in via the mouthpiece. The check valves are not perfectly sealed so given a little time, water can get past them. If you are using the C clips, it is possible they are not tight enough. In any case, water in the cans isn't really a big deal as long as it's cleaned out. I prefer a different cleaning method, if saltwater is left in the cans, it can cause a good bit of damage. This is what I do to ensure I get it all out. I am curious what other think. I do step 1 after every dive day, I go to step 2 after the dive trip is over, be it a day or a week.
1. Rinse the reg on the boat or dock, if possible flow water over the reg and into the mouthpiece, making sure the exhaust side is down. Shake the
reg to remove as much water as possible.
2, Back in my home/room I remove the hoses from the cans and flush them with warm water making sure I fill them completely to get any salt water
out of them. I sling them the remove as much water as possible then leave them to dry hang so that any remaining water can drain out. I go back
by for a few additional rounds of slinging any remaining water out.
3. Next, fill the cans with warm water and slosh it around, dump it out and repeat several times. This removes any salt water that got into the cans
it's common for some to get in and if not removed can cause a lot of damage. I know some are thinking OH NO water in the cans but think
about the design for a minute and you will realize the inside of a DH can is no different than the inside of a single hose reg. We all rinse the
interior of our single hose second stages.
4. If the cans have a band clamp, I take them apart and dry them, otherwise I set them with the supply horn down so any remaining water can
5 After a day or 2 of drying, I store them with the hose off in a container that will allow some air flow.