Nothing Broke — The Season Changed

There's a pattern in plumbing that shows up every September in the Twin Cities: a run of small household complaints that all seem to start within a couple of weeks of each other. The shower gets cold sooner. A drain that was fine in July starts gurgling. Something under the kitchen sink is damp. The basement smells faintly like a sewer.

It feels like a run of bad luck. It usually isn't. In most of these cases nothing failed — the operating conditions changed, and a system that was coping fine all summer stopped coping.

This post is the companion to the fall plumbing checklist. That one is the to-do list for prepping a house before the first freeze. This one is about the symptoms you're noticing right now and what's actually behind them.

The four things that change in September

Essentially every seasonal plumbing complaint traces back to one of these:

• Incoming water gets colder. Ground temperature drops through the fall, and the water arriving at your house drops with it.
• Air temperature swings hard day to night. A 75°F afternoon and a 42°F night in the same 24 hours means everything in the house is expanding and contracting.
• Indoor humidity falls. The furnace starts running and the air inside the house dries out.
• The yard fills with debris while roots are still growing. Leaves come down, and tree roots keep chasing moisture into late season.

Each one produces a distinct set of symptoms. Here's what they look like from inside the house.

"We're running out of hot water faster than we used to"

This is the most common fall complaint, and the explanation is straightforward arithmetic.

Your water heater doesn't heat water to a temperature so much as it raises water by a number of degrees. In Minnesota, municipal water typically arrives in the 60s in late summer and falls toward the 40s by late fall as the ground cools. The setpoint on the tank doesn't change — so the climb the heater has to make gets steeper.

The tank still holds the same number of gallons. It just takes longer to reheat them, so back-to-back showers run short in a way they didn't in August. On a healthy heater that's a seasonal adjustment, not a defect.

The catch is that this is also how a struggling heater announces itself. Sediment buildup, a failing dip tube, or a heating element on its way out can all hide during the easy months and become obvious the moment the workload increases. If the drop-off is dramatic rather than gradual, or the water is taking much longer to recover than it used to, that's worth looking at before winter — not because it's urgent today, but because a tank that gives out in February is replaced on the emergency schedule rather than yours. We've written up what replacement actually costs in St. Paul, including the Minnesota code requirements that surprise people.

"There's a new drip that wasn't there last month"

Temperature cycling is hard on connections. Metal expands when it's warm and contracts when it's cold, and September in the metro delivers that cycle every single day — a warm afternoon, then a night in the 40s.

The fittings that give up first are the ones that were already marginal: packing nuts on old valve stems, compression fittings under sinks, angle stops behind toilets that haven't been turned in fifteen years, and the connection at the top of a water heater. None of these fail dramatically. They weep.

Two things worth doing about it:

• Look before it's a stain. Take a flashlight under every sink and behind every toilet once this month. Dry paper towel pressed against the fitting will tell you more than your eyes will.
• Don't crank on it. The instinct is to tighten the nut until it stops. On old brass and worn washers, that's how a weep becomes a spray. Snug is the ceiling.

"The basement smells like sewer all of a sudden"

Nine times out of ten this is a dried P-trap, and it's the easiest fix on this list.

Every drain has a U-shaped bend holding a small amount of water. That water is the only thing standing between the sewer line and your living space. Drains that get used daily refill themselves. Drains that don't — basement floor drains, laundry sinks, the guest bathroom nobody uses, a bar sink — slowly evaporate.

Fall accelerates it. The furnace kicks on, indoor humidity drops sharply, and standing water in a trap disappears faster than it did in humid July air.

Pour two or three cups of water down every drain in the house that doesn't see regular use, including floor drains. A splash of mineral oil on top slows future evaporation in drains that go months between uses. If the smell is still there a day later, the trap isn't the problem and it's worth having the venting and drain lines looked at.

"Drains are slower than they were this summer"

Fall backups often have a different cause than summer backups, and it's worth knowing which you're dealing with.

Outside, leaves are filling gutters, window wells, and yard drains. In a lot of older St. Paul homes, downspouts and drainage were tied into the system in ways that made sense decades ago and don't now — so a yard full of wet leaves can end up affecting what happens in the basement.

Below ground, tree roots are still active. Roots chase moisture, and a sewer lateral with a hairline crack is the most reliable water source in a dry autumn yard. A line that was passing marginally in July can be genuinely obstructed by October without anything changing inside the house.

The distinguishing signal is repetition. One slow drain in one fixture is usually a local clog. Multiple fixtures backing up, a floor drain that burps when the washer empties, or a backup that returns a few weeks after being cleared — that points at the main line. Roots in the sewer lateral are the usual explanation in older St. Paul neighborhoods, and that post also covers the city loan program most homeowners don't hear about until after they've paid.

"The sump pump hasn't run in weeks"

Fall is the quiet season for sump pumps, which is exactly the problem. A pump that sat idle from August through November is the one most likely to fail when a midwinter thaw or a heavy fall rain finally calls on it.

Dump five gallons of water into the pit and watch what happens. The float should rise, the pump should start, the pit should clear, and the pump should shut off cleanly. Then walk outside and confirm the discharge line is clear, isn't crushed, and isn't pointed back at the foundation — and think about where it'll be once there's a snowbank there.

If you're not sure whether past basement water was a pump issue or something else, the difference between a sewer backup and a sump pump failure is worth understanding before you're standing in it.

What's urgent, what's seasonal, what can wait

If you're unsure whether something needs a call tonight or can wait until morning, this guide sorts that out.

Why fall is the cheap window

There's a practical reason to act on any of this in September or October rather than filing it away.

Anything requiring excavation — a sewer lateral repair, a water service issue, an outdoor line — gets meaningfully harder and more expensive once the ground is frozen. Anything that's a slow leak now becomes a freeze risk once temperatures stay below freezing. And anything involving a plumber's schedule is easier to book in October than during the first hard cold snap, when every call in the metro is an emergency call.

The problems in this post are mostly small. That's the whole point of writing them down in September. They're small now.

If that pass turns up something you'd rather not chase down yourself, the next step is a licensed plumber — and getting a couple of comparable quotes on it is easier now than it will be in January.