Closing Up the Summer/Lake House: Winterizing Your Water System
Pioneer Water Treatment · Oct 21, 2026
If your place near Fennville, South Haven, or Saugatuck sits empty from November to May, the next three weeks decide whether you come back to a working water system or a flooded basement.
West Michigan usually sees its first hard freeze in early to mid November. Lake effect gives the shoreline a few extra days of mild air, which is exactly what makes seasonal owners complacent. One cold snap in an unheated house is all it takes.
Here's what makes water treatment equipment different from the rest of the house. Winterizing plumbing is familiar territory — drain the lines, blow them out, pour antifreeze in the traps. But a softener, an iron filter, and a UV system each hold several gallons of water inside sealed tanks that do not drain on their own. Shut the water off, drain the pipes, lock the door, and every one of those tanks is still full. Water expands about nine percent when it freezes. A cracked resin tank or a split control valve is not a repair. It's a replacement, and it's usually discovered in April when the system is turned on and water starts coming out of places it shouldn't.
This guide walks through closing a seasonal home properly, with a focus on the treatment equipment most checklists skip.
What a freeze actually destroys
Most of the damage isn't to pipes. It's to the equipment standing next to them.
Equipment
What freezing does
Repair or replace?
Softener control valve
Internal pistons and seals crack; the plastic body splits
Replace — often the costliest single part
Softener resin tank
Fiberglass shell cracks, resin bed is ruined
Replace
Brine tank
Cracks at the base; salt bridges form in damp cold
Replace tank, or break up the bridge
Iron or sulfur filter
Same as the softener — valve and tank both at risk
Replace
Sediment filter housing
Clear plastic housings split readily
Replace housing
UV system
Quartz sleeve and lamp crack; chamber splits
Replace sleeve and lamp at minimum
Reverse osmosis unit
Membrane is destroyed; housings and the small tank crack
Replace membrane and any split parts
Pressure tank
Bladder ruptures, tank fails
Replace
Water heater
Tank splits, usually found only when refilled
Replace
Well pump and pitless adapter
Below frost line, generally safe; above-grade piping is not
Varies
One detail worth understanding: the damage frequently stays hidden. A hairline crack in a resin tank or valve body leaks nothing while the system sits empty and dry. It leaks in April, under pressure, in an empty house, sometimes for days before anyone notices.
That's the scenario worth avoiding. The precautions below take an afternoon.
First decision: heat on, or drain it down?
Pick one of these deliberately. The in-between — heat set low, nothing drained, nobody checking — is where most of the failures we see actually come from.
Leave the heat on (55°F or higher). Simplest option, and the right one if you visit in winter, rent the place out, or have a finished basement with equipment you'd rather not disturb. The system stays wet and ready. The risks are a furnace that quits, a propane tank that runs dry, or a multi-day power outage — any of which turns an unprotected house into a drained-the-hard-way house. If you choose this, you need two things: a freeze alarm that texts you (a basic cellular temperature sensor runs well under a hundred dollars), and someone local who can get inside within a few hours.
Full drain-down. The right call if the place is genuinely closed until spring, or if you'd rather not depend on a furnace running unattended for six months. Nothing can freeze if nothing is holding water. It takes longer to close and longer to open, and the well system needs sanitizing in spring after sitting dormant.
The partial approach deserves a warning. Shutting the water off at the main but leaving the treatment equipment full is the most common mistake we find. The softener, the filters, and the pressure tank all stay loaded with water. People believe they've winterized, and they've protected almost nothing.
For most unoccupied lakeshore homes, the full drain-down is the safer bet. The rest of this covers that path.
The shutdown sequence
Order matters here. Draining in the wrong sequence can leave water trapped in exactly the places you were trying to empty.
Kill power to the well pump and the water heater. Breaker off for both. An electric water heater that fires with an empty tank destroys its element in minutes; gas gets switched to the pilot or vacation setting.
Close the main shutoff from the well or pressure tank.
Open every fixture in the house — hot and cold, every bathroom, kitchen, laundry, utility sink, outdoor spigot. Start upstairs and work down so gravity helps.
Drain the water heater through its bottom valve to a floor drain or outside. Expect this to take a while on a 50-gallon tank, and remember that sediment often slows the last few gallons.
Drain the pressure tank at its valve.
Drain the treatment equipment. The softener and each filter in turn — the next two sections cover exactly how.
Blow out the lines with compressed air at 40 to 50 PSI. Higher pressure risks damaging fittings. This is the step that clears low spots a gravity drain can't reach, and it's the one most worth paying someone to do if you don't own a compressor.
Drain the washing machine and dishwasher supply lines and internal pumps. Disconnect the hoses at the washer.
Pour RV antifreeze into every trap — sinks, showers, tubs, floor drains, and the toilet. Flush the toilets, sponge out the tank and bowl, then add antifreeze to both.
Shut off the ice maker and drain its line. These freeze and split constantly, and the line runs somewhere inconvenient every time.
Leave the fixtures open all winter so any residual water has an escape route if it expands.
Use RV or propylene glycol antifreeze, the pink kind. Never automotive antifreeze — it's toxic and it will contaminate your well system.
Winterizing the softener
A softener holds water in three places, and all three need attention.
The resin tank holds the bed of beads and the water around them. The brine tank holds salt and several inches of standing water at the bottom. The control valve on top holds water in its internal passages — and this is the part that cracks first, because the passages are narrow and the plastic is thin.
Work through it in this order:
Run a manual regeneration before you shut the water off. This flushes the resin bed clean, so it doesn't sit all winter loaded with hardness minerals and iron. Let the cycle finish completely.
Put the valve in bypass. There's a bypass lever or two valves on the plumbing behind the unit. This isolates the softener from the house lines.
Unplug the control head. No power, no clock, no attempted regeneration in an empty house.
Drain the resin tank. Disconnect the drain line and the inlet and outlet connections and let it empty. On many units you'll need to tip the tank slightly — carefully, because a full one is heavy — to clear the last of the water. Some models have a drain plug at the base of the valve; pull it if yours does.
Empty the brine tank. Scoop out the salt, then siphon or sponge out the water at the bottom. Dry it as well as you can. Salt left in a damp cold tank forms a solid bridge over winter, and in spring the unit will appear to run while drawing no brine at all.
Remove and drain the brine well and float assembly if the unit has one.
Blow out the valve passages with low-pressure air if you have a compressor. This is the step that saves control valves.
Two mistakes we see regularly. First, bypassing the softener but leaving it full — bypass isolates the unit, it doesn't drain it, and the water inside freezes exactly as it would have otherwise. Second, leaving a full brine tank, assuming salt keeps it from freezing. The salt saturates only the water immediately around it; the rest freezes, and the tank cracks at the base.
If your softener sits in an unheated crawlspace or an outbuilding — common along the lakeshore — treat this as mandatory rather than optional.
The rest of your treatment equipment
Everything else in the chain holds water too. Here's what each one needs.
Iron and sulfur filters. These winterize much like a softener. Run a manual backwash, bypass, unplug, then drain the tank and valve. Air injection models have an air pocket at the top of the tank that must be released as you drain — otherwise the tank holds a vacuum and won't empty fully.
Sediment filter housings. Unscrew the housing, dump the water, pull the cartridge, and leave the empty housing loosely threaded on. Don't store a used cartridge wet over winter. Clear plastic housings are among the first things to split in a freeze.
UV systems. Unplug the unit. Drain the chamber. Pull the quartz sleeve and the lamp, and store the lamp somewhere warm and dry — it is fragile and it has a service life measured in running hours. A frozen chamber with a sleeve inside usually means replacing both. Note your lamp's install date while you're down there; most need annual replacement anyway, and spring is the natural time.
Reverse osmosis systems. Close the feed valve, open the faucet, and drain the storage tank completely. Remove the membrane and the filter cartridges and store them in a sealed bag somewhere above freezing. A frozen RO membrane is finished. These sit under a kitchen sink against an exterior wall more often than not, which is one of the coldest spots in the house.
Carbon filters. Drain as with any other tank. Carbon that sits wet and warm grows bacteria, so plan on replacing the media if the system has been in service a few years.
Chemical feed pumps. Drain the solution tank and flush the pump head with clean water. Chlorine or peroxide solution left to freeze will split the pump head.
Opening up in spring
A well that sat idle for six months is not the same well you shut down. Plan on sanitizing and retesting before anyone drinks from it.
Stagnant water in a well, a pressure tank, and a hundred feet of idle pipe is ideal territory for bacteria. Iron and sulfur bacteria establish themselves in dormant systems routinely, and coliform can enter through a well cap that shifted over a winter of freeze and thaw. The water will look and taste completely normal either way.
Bring it back in this order:
Inspect outside first. Check the well cap for a tight seal and intact gasket. Look for frost heave around the casing, and clear away any debris or burrow holes near the wellhead.
Close the fixtures and the drain valves you left open.
Refill the water heater completely before restoring its power. An element fired dry is destroyed immediately.
Reinstall filter cartridges, the RO membrane, and the UV sleeve and lamp. Fresh cartridges, not last fall's.
Restore power to the pump and let the system pressurize slowly. Walk the house and look at every connection, especially around the treatment equipment.
Shock chlorinate the well and run the chlorine through every fixture. Let it sit the recommended dwell time, then flush until the chlorine smell is gone.
Take the softener out of bypass, refill the brine tank with fresh salt, restore power, and run a manual regeneration.
Test the water before drinking it — coliform bacteria at minimum, and nitrates if you're in the farm country inland from the lakeshore.
One caution on step 6. Chlorine damages softener resin and UV lamps. Leave the softener and the UV system in bypass while you shock the well, and only bring them back online after the system is flushed clear.
