A treatment system is easy to forget until water is running across the floor. The person who answers that emergency may be a family member, a house sitter, or a neighbor with a key, and they may have never seen the equipment. A one-page map of the water loop gives them a fair chance of closing the right valve on the first try.
What the map has to show
Start at the point where water enters the house, either the utility meter or the well pressure tank, and follow the line through each piece of equipment in the order water actually passes through it. Mark the main house shutoff, the inlet valve to the treatment equipment, the outlet valve back to the house, the bypass valve if the unit has one, and any drain line. Add every electrical item that feeds the equipment, such as a pump, a UV lamp, or a control head, and note which breaker or outlet powers it. Also mark the shutoff for the water heater if it sits on the same line.
How to make it readable
Use plain words on the labels rather than model names: treatment in, treatment out, bypass, main shutoff, drain. Put a small tag or a strip of tape on each valve that matches the drawing. Take a photo of the equipment and the valves, then sketch the loop by hand, because a sketch with arrows is easier to follow in a hurry than a parts list. Tape a copy inside the utility closet door or the cabinet where the equipment sits, and keep a second copy with your paperwork.
Test the map before you need it
Walk the route with another adult. Have that person read the map while you point to each valve and breaker, and check that the labels match the drawing. If any valve on the drawing cannot be found, or if you cannot tell which way it turns, mark that as an open item. Do not guess at valve operation during a leak. Ask your installer or service provider to show you the safe sequence, and to confirm whether the bypass is a full bypass or a partial one. A partial bypass can leave some water flowing through the equipment, so the person closing valves needs to know the difference.
What to ask your provider
When you hire anyone to work on the system, ask them to check the map against the installed equipment. Ask which valves should be closed for service, where the drain line goes, whether the unit needs power while the water is off, and how to restore flow afterward. Ask them to write the answers on the drawing, not just tell you verbally. If you are comparing providers in the Missouri Water Experts directory, a provider who will prepare or update a drawing for you is showing you how they handle the work after the install.
Keep it current
Every time equipment is added, moved, or replaced, update the drawing and the labels the same day. A map that shows the old layout is worse than no map, because it sends the next person to the wrong valve with confidence. Write a short note on the drawing about what changed and who made the change. Store the current copy with your equipment record and make sure at least one other person knows where it is kept.