How far should clean water bottles be filled?

I understand that when your operatory has a clean water bottle system that it can be frustrating when that bottle runs out. Consequently, many assistants have had a tendency to fill their water bottles all the way to the top before screwing them onto the clean water systems. Clean water systems are fairly simple devices. They consist of a manifold that the bottle screws into, a water feed tube (Hangs down inside of bottle), and a small hole near the top of the bottle where regulated air (approximately 40PSI) enters the bottle. As strong as the tendency to fill the bottle to the top is, I want your staff to refrain from this practice. Here’s why:

#1 As a bottle is screwed onto a clean water system manifold, the feed tube displaces water as it enters the bottle causing water to spill over causing a mess, especially if the solution in the bottle is a waterline cleaning agent.

#2 If a bottle is completely full of water when screwed onto a clean water system manifold the water is at such a high level within the bottle that it comes into contact with the air inlet hole of the manifold. If the bottle gets pressurized and then de-pressurized, the water tends to get into the air line. This water can damage bottle on/off toggles, pressure regulators, as well as even cause water to come out when the air button is pressed on a syringe. This condition is referred to as air/water crossover and is something we want to avoid if at all possible.

Ah, so here comes the answer to the question that everyone is asking right now. “How full should I fill the clean water bottle?” — We suggest that you stay down about 1.5 inches from the neck of the bottle. Some of the newer clean water bottles actually have a raised fill line molded onto the bottle. We basically want to make sure that there is a gap of air near the top of the bottle even after it is screwed onto the manifold.