A softener does not run on its own supply. The brine tank takes a bag or two of salt, and each regeneration pulls some of that salt down. Salt refill is a recurring task with an owner, a rhythm, and a few checks. Most of the trouble with it comes from nobody being named to do it.
Find the level and the fill line
Look into the brine tank with a flashlight now and then, and note where the salt sits compared with the water line. Your owner's manual will say how full to keep it and where the fill line is. Do not pack salt above that line. If your unit has a level window or a float, learn how it reads before you need it.
Write down each fill
Keep a short note on the unit or in your phone with the day you added salt and how many bags went in. After two or three fills you will know how long one bag lasts in your house. That number tells you when to reorder, and it gives a service visitor something concrete to look at if salt use changes.
Set the reorder trigger
Pick a level mark or a time interval that tells the buyer to order more. A trigger works better than memory. Write it on the note, tell whoever buys the salt, and keep one spare bag in the house in case a delivery runs late. If more than one person in the house shops, decide in the same conversation who owns the reorder.
Choose the salt type from the manufacturer's list
Salt comes as pellets, crystals, or compressed blocks. Check the owner's manual for which forms it accepts and whether it calls for any specific grade. Ask the installer or the seller the same question before buying in bulk. If the manual is missing, the manufacturer's support line or the paperwork from the installer usually has the answer. Do not switch types partway through a supply without checking first.
Store the bags so they stay usable
Keep bags in a dry place, out of rain and standing water, and keep them closed until you pour. Salt that absorbs moisture can clump in the bag before it reaches the tank. Keep bags off the floor if the floor sweats or gets wet in a basement. Lift with your legs, not your back, and get help with heavy bags.
Check for bridging and mushing
Two problems can show up even when the salt level looks fine. A bridge is a hard crust of salt over an empty space, so the tank looks full but no brine forms. Mush is a soft sludge at the bottom that keeps salt from dissolving. If the level is high and the unit stops regenerating, or water stops softening, look into the tank before you add more salt. Break a bridge gently with a broom handle. Call for service if you find sludge or cannot clear the tank yourself.
Ask the seller these before the first order
Ask whether they deliver, what the minimum order is, and how the bags are packed. Ask whether they bring salt on a set schedule, which helps a household that does not want to track the level. Ask what happens if a delivery is missed or the wrong type arrives. Get the answers in writing or on the invoice so the record stays with the rest of your unit paperwork.
For the wider sequence of owning and keeping a unit, see the Missouri Water Softener Buyer's Guide.