Somebody went and measured what the septic tanks in this town are doing to Merrymeeting Lake. The answer came back eighteen percent.
In September of 2019 the Cyanobacteria Mitigation Steering Committee — a joint New Durham and Alton outfit — published a watershed management plan for Merrymeeting Lake and the river below it. FB Environmental built a loading model and traced the phosphorus in the lake back to where it comes from. Watershed runoff, fifty-six percent. Rain landing on the surface, nineteen. Septic systems, eighteen percent — fifty kilograms a year. Third largest source in the whole budget. Waterfowl finished behind us, which we have decided not to feel good about.
Here’s why that number lands harder here than it would somewhere else. Merrymeeting flushes at a rate of 0.3, which means the entire volume of the lake — 1,242 acres, a hundred and thirty-five feet down at the deep hole — replaces itself roughly once every three years. Compare that to Marsh Pond just downstream, which turns over fifty-four times a year and behaves more like a river than a pond. Whatever arrives in Merrymeeting settles in and stays a while. The plan holds the lake to a goal of 3.5 parts per billion of phosphorus, and the modeled figure for what it ran at before anybody built on it is 1.9. Very clean water, very tight number, and the margin between the two gets counted in single kilograms.
None of that is a lecture. It’s a scheduling argument. Runoff and rainfall aren’t anybody’s to fix on a Saturday. A tank is. Pump it on the two-to-three-year cycle the state recommends and the solids stay on the settled side of the outlet tee instead of drifting out into a leach field that then does a little less of its job every year afterward. That’s the entire mechanism. It isn’t complicated, it isn’t expensive, and a lake that replaces itself every three years is a reasonably convenient way to remember how often to call.
Write the date on the inside of the basement door with a marker, or on the tank riser lid itself. Sounds crude. It works better than any filing system we’ve seen, and it survives the sale of the house — which matters more here than most places, because the next owner of a Merrymeeting property is going to get asked what they know about that system sooner or later.
First we find the lid and dig it out. On plenty of New Durham properties that’s the longest part of the visit, because a fair number of these tanks went in during the seventies and the one person who knew exactly where has been gone for twenty years. If you know, say so. If you don’t, we probe for it, and we don’t bill you for the ten minutes of hunting.
Then it all comes out. Not the liquid skimmed off the top — that’s the shortcut that makes a truck look busy and leaves the sludge layer sitting on the bottom doing you no good at all. Empty means we can read what there is to read: the inlet baffle, the outlet tee, whether there’s an effluent filter and whether anyone has ever once cleaned it, the state of the concrete at the waterline where it always goes first. We measure the sludge before we pull it, so what we tell you about your interval comes off your tank instead of off a brochure.
You end up holding the date, the gallons, the sludge depth, the condition notes, and the lid location measured off something that isn’t going to move — a foundation corner, the well cap, a rock big enough to still be there in 2050. Keep it in a drawer. The watershed plan recommends the town build and maintain a septic database through Code Enforcement, and if that ever comes together, households that can produce a maintenance history are going to have an easier time of it than households that can only remember a truck being here once, maybe, during the Obama years.
A standard 1,000–1,250 gallon tank runs $300–$500 to pump. Where you land inside that comes down to tank size, how far the truck can get from the lid, and how much digging the lid needs. You get the figure before we roll, not after. If we open it and find something that changes the job — a collapsed baffle, a second compartment nobody mentioned, an old steel tank you’d rather not hear about — we stop and tell you what it costs before we carry on.
On its own, no — one tank is a rounding error, and we’re not going to pretend otherwise. But look at the arithmetic in the plan. Total load to Merrymeeting is 284 kilograms a year, septic accounts for fifty of it, and Objective 1 asks for a reduction of sixteen. That target is about a third of the whole septic contribution. No single household gets there, and it doesn’t happen without most of them. If that argument does nothing for you, here’s the selfish one: a field silted up by solids that escaped an unpumped tank is a five-figure replacement, and a pump-out is three hundred dollars.
Probably longer, but not as much longer as people assume, and the reason is worth knowing. Ten weekends of heavy use is not the same as ten weekends of light use — six people over a long weekend put more through a tank in three days than a retired couple do in three weeks. Meanwhile the bacteria that break solids down want steady feeding and don’t get it in a place that sits empty from October to May. What we do is measure your sludge and give you a real number, which for most seasonal places up here lands somewhere between four and six years.
Usually, and the honest answer depends on the driveway rather than the lake. A loaded pump truck is heavy and it’s tall, and a fair number of the drives off the shore roads were laid out for a pickup in 1968 and have had spruce closing in on them ever since. We carry hose for exactly this. Tell us grade, width and overhead limbs when you book and the right truck shows up. It’s a routine question, not a warning sign.
No, and anybody telling you otherwise is selling something. Pumping protects the field, it doesn’t clean it. The tank’s whole job is settling solids so that what reaches the field is liquid; when the tank gets full enough that solids start carrying over, they lodge in the soil pores and stay there. That damage is cumulative and it’s permanent. Nothing pumped out of the tank afterward brings the soil back.
Same-week scheduling, straight prices, and a crew that knows the Lakes Region.
Tell us where the property is and what's going on. We'll get right back to you with a straight price.
We reply to every request within 2 business hours — emergencies first.
Lakes Region