The Short Version
Find out where the water enters, fix the outside causes while the ground is still diggable, and test the sump now rather than in March. That is the whole page. The order matters, because the first item decides whether the second one is relevant at all.
The spring flood gets all the attention here, and reasonably so — it is the most predictable event in this trade. But March is the worst month to do anything about it. The ground is saturated or frozen, every contractor in the region is booked, and decisions get made while somebody stands in two inches of water. October is the opposite of all three, and it has one further advantage that no other month offers: the ground outside is already wet enough to show you what your basement actually does.
The seasonal plan for the rest of the year is in getting ready for the melt. This page is the October detail.
Frozen Ground Closes the Cheap Half of This Trade
Almost everything inexpensive we do happens outside, in soil — and in a few weeks you will not be able to dig it. That is the real reason autumn matters, and it is not a sales argument, because the work it is urging you toward is the work with the smallest invoice attached to it.
New Hampshire frost depth is commonly taken as about 48 inches for design purposes. Long before it reaches that, the top foot is hard enough that regrading becomes an excavator job rather than an afternoon with a shovel, and a downspout trench stops being worth starting.
Wants doing in the next few weeks
All of it outside, all of it soil, all of it cheap. After freeze-up these wait for April.
- Gutter clearing and downspout correction — $0–$400
- Regrading where ground has settled toward the house — $400–$1,500
- Window well drainage and covers — $200–$1,200
- Exterior excavation, footing drains, exterior membrane
- Clearing and re-laying a sump discharge line so it drains properly
Available all winter anyway
Interior work, inside a heated building. No rush from the weather — but several times the cost.
- Sump pump installation with pit — $1,200–$3,000
- Battery backup system — $900–$2,000
- Crack injection, per crack — $400–$900
- Partial interior drainage — $3,000–$7,000
- Full interior perimeter drainage — $10,000–$15,000+
Every figure above, with its sources, is on our New Hampshire basement data page.
Read those two columns next to each other and the point makes itself. The column that closes this month tops out at $1,500. The column that stays open all winter starts where that one ends. We would far rather sell you the left-hand column, and October is when we still can.
The Bucket of Water, Done Properly
A pump that has sat untouched since April is exactly the pump that does not start in March. Testing it now is the single most valuable thing on this list, and it takes about ten minutes.
The test most people do is to lift the float by hand and listen for the motor. That proves the motor turns. It does not prove the pump works, because there are three separate failures between a motor that turns and a basement that stays dry.
Fill the pit, not the floor
Pour water into the pit until the float rises on its own and the pump starts. Using the real float on real water is the point — a float that is snagged on the pit wall, on a cable, or on a lip of accumulated silt will lift happily under your hand and never lift on its own. Switch failures are the most common sump failure there is, and they are invisible to a hand test.
Go outside and watch the discharge
Water must visibly leave the pipe. A pump that runs and discharges nothing is working against a blockage somewhere between the pit and the outlet — a crushed line, a collapsed section, a nest in the outlet, or silt settled in a low spot. The motor sounds completely normal while this is happening, which is exactly why this step exists.
Confirm it shuts off by itself
It should stop once the pit is down, and stay stopped. A pump that keeps running has either a float that is not falling or a pit that is refilling, and both want understanding before winter rather than during it.
Listen as it stops
If you hear water running back down into the pit after shutdown, the check valve is not seating. The pump is then lifting the same column of water repeatedly, cycling far more often than it needs to, and wearing out early. A check valve is a cheap part doing an important job badly.
Test the backup by unplugging the pump
Not by looking at the indicator light. Unplug the primary pump, pour again, and confirm the backup actually takes over and moves water. Lead-acid batteries lose capacity quietly over a few years and a charge light says nothing about whether there is a usable reserve behind it. If there is no backup at all, fit one now — the outage and the meltwater arrive in the same storm.
What the bucket does not tell you is capacity. It proves the pump is alive; it says nothing about whether it can keep up with your worst week, because you poured in a bucket and March arrives with a hillside. That is a sizing question rather than a testing one — work it out with the sump sizing tool, and the components that matter more than the pump itself are in the sump pump buying guide.
Gutters: Clean Them Late, Not Early
The gutter clearing that matters is the one done after the leaves are actually down. In this region that is generally late October into November, not the first crisp weekend of the month.
This sounds like a detail and is not. A gutter cleared while half the canopy is still on the tree is full again within a few weeks, and the clog that counts is whichever one is in place when the weather turns. Then the autumn mechanism takes over: a blocked gutter in November is a frozen gutter in December. Water backs up behind the ice, leaves the system at the eaves, and lands in a concentrated vertical line against one spot on your foundation for the rest of the winter.
That is surface water — the cheapest category of problem in this trade — arriving in the only season when you can no longer go outside and fix it. Which is the whole argument of this page in one example.
So: clear them once the trees are bare, then check that every downspout discharges at least six feet from the wall. Not onto a splash block, not into a bed of decorative stone against the house, and not into a buried line nobody has confirmed still runs. An extension costs very little and frequently resolves the entire complaint. If a buried line is involved and you cannot prove where it goes, assume it goes nowhere until somebody demonstrates otherwise.
Walk the Perimeter on a Wet Day
Ground that slopes toward a house is the second-cheapest fix available and the most commonly missed, because it developed slowly enough that nobody noticed. Backfill around a foundation keeps settling for decades after the house is finished, and a grade that shed water away in 1978 can be running it back toward the wall now.
Do this walk during or just after rain, when water shows you its own route rather than leaving you to guess:
- Ground that has settled into a dish or a channel against the wall, or sits lower at the wall than a few feet out
- Standing puddles that are still there an hour after rain stops
- Mulch, soil or stone beds built up against the siding, holding water at the sill
- Window wells with no outlet — a well without drainage is a bucket, and it empties into your basement
- A patio, walk or apron that has tipped back toward the house
- Where a neighbouring slope, a drive or a ditch delivers runoff onto your lot
The remedy is unglamorous: build the ground back up so it falls away from the wall over the first several feet. It wants doing with soil rather than with the free-draining material people reach for, because a gravel collar against a foundation is a route down, not a barrier. And this is soil work, which means it is October work.
Grading and gutters are the two things homeowners most often skip because they feel too simple to be the answer. They are the answer more often than anything else on our price list.
Where It Comes In Decides the Fix
Go down to the basement during the next hard autumn rain, with a torch, and note where water appears. That single observation is worth more than any quote you could collect this month, and late autumn is when the ground cooperates: it has been wet for weeks, it has largely stopped absorbing, and the rain is heavier than anything the summer produced.
There are four answers, and they do not cost remotely the same.
Down a wall, from near the top
Surface water. Roof runoff, grading, a window well filling. This is the gutters-and-grading column above, and it is the outcome to hope for, because it is the one that is still fixable this month for a few hundred dollars.
At the joint where the floor meets the wall
Hydrostatic pressure — groundwater outside standing higher than your floor and pushing up underneath. No wall coating touches this. Nothing you do outside this month changes it either. It is interior drainage to a sump, it is a planned job, and October is for booking it, not rushing it.
Through a crack
Then the crack is the entry point and the real question is why it is there. Injection seals the leak. Whether anything beyond that is needed depends on what the crack is doing, which wants an engineer or an assessment with eyes on it — not a verdict from a website. Photograph it with something for scale and run it through crack triage.
Everywhere, in volume
A high water table doing what one does on a Lakes Region property sitting close to surface water. That is drainage and pumping, not sealing, and the autumn version is usually a milder preview of what March will deliver.
Write down what you saw, where, and how long after the rain started. Photograph it. If you take only one thing from this page beyond testing the pump, take that record — it is what turns a spring emergency into a summer appointment. The wet basement diagnostic turns those same observations into a likely cause and a cost band, and the mechanism behind all four patterns is set out on the data page.
If the walls are fieldstone, none of the sealing logic applies at all. An antique cellar was built to let moisture pass through while carrying load. Sealing or parging the inside face traps water in the stone, works at the mortar and drives moisture up into the sills and framing above — and the sills are the expensive part of that sentence. Manage the water instead: keep it away from the outside, give what gets in a controlled route out, keep the air moving. Where repointing is genuinely needed it is lime-based mortar matched to the original, never hard Portland mix. The full picture is in old stone foundations.
If You Are Closing a Camp Rather Than Settling In
On a seasonal building the priority inverts, because the flood happens in the one season nobody is there. The Lakes Region melt lands in March and April. A summer house is empty then, which is why so many owners here have no water history to report — not because nothing happened, but because nobody was present when it did.
So the October visit is the one that matters all year. Before the door is locked:
- Run the bucket test above, properly, including the backup — this is the pump that will run unattended for two months
- Confirm the discharge line has enough fall to drain fully between cycles, and that it ends clear of anything that will drift or bank over it
- Fit a water alarm, and a backup system if there is not one — $900–$2,000 — because on unoccupied property an unnoticed failure runs for weeks
- Get everything off the floor now. March is not an option if you are not in the state
- Arrange for somebody with a key to look at the building during the melt, and tell them what to look at
- Leave the space ventilated or dehumidified rather than sealed up damp
And while you are down there, read the walls. A horizontal staining or efflorescence line, a silt mark on the slab, rust starting at the base of anything metal standing on the floor — that line records how high water has stood, whoever was or was not home to see it. On a converted camp, check the whole underside too: a cellar under the original footprint and a crawl space under a later addition share air, so an exposed earth floor at one end is a common source of a musty smell at the other.
Questions
I have never had water in the basement. Do I need to do any of this?
The bucket test and the gutters, yes — they are ten minutes and an afternoon, and they are maintenance rather than repair. The grading walk is worth doing once so you know what your lot does. What you should not do is buy a drainage system against a problem you do not have. A dry basement in a region like this is usually dry for a reason, and the reason is normally the grading and the roof water doing their job. Keeping them doing it is the entire task.
Should I seal the inside of my basement walls before winter?
Only after you know where the water comes in, and on a fieldstone wall not at all. Interior coatings address damp passing through the body of a wall. They do nothing whatever for water arriving at the floor-wall joint under pressure, and they are actively harmful on an antique stone cellar, where they trap water in the wall and push it into the sills. A coating applied before the diagnosis is at best money spent on the wrong problem and at worst a new one.
Is there any point getting an assessment this late in the year?
Autumn is one of the two best times to have somebody look, for the same reason it is a good time to look yourself: the ground is wet and the basement is doing whatever it does. Seeing it active beats hearing it described. What usually follows from an autumn assessment is a small amount of exterior work booked immediately and the larger job scheduled for summer, which is both the cheaper sequence and the calmer one.
The ground is already frozen where I am. Have I missed it?
You have missed the digging, not the rest. Clear the gutters anyway, extend a downspout above ground with a flexible section even if you cannot bury it, keep piled and ploughed snow off the foundation through the winter, and run the pump test. Then use the winter to settle what the exterior work should be, so it goes in during the first workable weeks of spring rather than queuing behind everyone who waited until the melt.
Should a downspout extension be buried or left on the surface?
Buried is better and above ground is fine, and the choice is largely about what the next few weeks allow. A buried line carries water further out, survives mowing and does not get moved by whoever is strimming, but it is a trench, which makes it this month's work or April's. A surface extension does the same hydraulic job for a fraction of the effort and can be fitted in any weather — so if the ground has gone hard, fit one above ground now and bury it in the spring rather than leaving the water at the wall for a winter. Whichever you use, the thing that matters is where it ends, not what it is made of.
Can you tell me whether my crack is serious from a photograph?
We can tell you a great deal from a photograph with something for scale in it — pattern, width, direction and whether it is passing water are all readable — and we will say honestly which category it falls into and whether it warrants a proper look. What nobody should give you over the internet is a determination about the structure itself. That is an engineer's inspection, and if yours is one of the patterns that warrants one we will say so plainly rather than quoting you a sealant.