I'm going to ASSUME here that you are attempting to install one of these on your lawnmower deck?
Some here like me, find the water "wash" system not only ineffective, but tend to induce more corrosion/rust to decks than those that don't use them.
Water is also not good for the bearings when it gets in past the worn spindle seals.
it is always best to scrape the deck clean using something like a putty knife/air hose to clean the deck underside.
But few do it in todays throw away world.
Just something to ponder.
Under deck washes have been around since before the 60's so it is not new tech.
Now the front mounted flip up decks are easy to clean but not everyone has those.