The Surge You Can’t Schedule

The Well Pump — No Power Means No Water

If you are on city water, an outage costs you air conditioning. If you are on a well — and a great many rural and semi-rural households are — an outage costs you water. Every flush, every faucet, every glass. The well pump is not a comfort item. It is the reason many rural households need a generator at all.

What it actually pulls

A common ¾-horsepower pump runs on roughly 1,500 watts — and starts on three to four times that. Our calculator carries it at about 4,500 starting watts, and like the air conditioner, that surge is the number your generator has to survive, not the number on the pump's box. Bigger pumps and deeper wells pull more. If your pressure switch clicks and the lights dim, you have met your surge.

Two things the box will not tell you:

• Most well pumps are 240-volt. A small 120-volt-only inverter generator — the kind that is perfect for the refrigerator and the CPAP — cannot run one at any wattage. If the well is on your list, you are shopping for a unit with a 240V outlet, and that changes which shelf you are standing in front of.
• The pump is usually hardwired. There is no plug to move to the generator. Connecting it safely means a transfer switch or an interlock, installed by an electrician — a few hundred dollars, done once. What it does not mean, ever, is feeding the generator back through a dryer outlet with a homemade double-ended cord. That trick energizes the utility lines outside your house and can kill the lineman working to get your neighborhood back on. There is no version of this article, this site, or this hobby where that is acceptable.

The quiet way a small generator kills a pump

Here is the part nobody prints on the generator box. When a generator is too small for the pump it is feeding, its voltage sags under the strain — and electric motors have a mean habit: when the voltage goes down, the amps they pull go up. So the pump strains, runs hot, and slowly cooks its own motor. Not with a bang. Over minutes and starts, while everything technically “works.”

You can hear it happening. The engine lopes and groans, and the pump sounds like it is fighting instead of humming. Owners who have lived through it describe exactly that sound — and say they did not understand what it meant until the pump was dead. If you hear it, shut it down. That sound is a pump being eaten.

One well company owner put it more cheerfully than we will: he said he loves portable generators, because undersized ones send him pump-replacement business every year, like clockwork. Let some other family be that business. This is the whole reason this site sizes generators up and never down. Being a little over costs you some money, once. Being under can cost you the pump, the fuel you burned killing it, and your water — all in the same week.

One sizing footnote while we are here: if you buy a dual-fuel generator and plan to run it on propane — a fine choice, propane keeps forever — know that the same machine makes about 10% less power on propane than on gasoline. Size for the fuel you will actually burn, not the bigger number on the box.

The box that listens so you don’t have to

The ear test above has one weakness: it only works while you are standing next to the generator. So here is the good news — there is a little box that does that listening for you, every second, all year. It is called a pump protection device: a box about the size of a paperback that gets wired in next to the pressure switch, where it watches two things at once — how hard the motor is working, and what the voltage is doing.

When something goes wrong — the voltage sagging low the way an overloaded generator sags, or spiking high, or the well running low so the pump spins with nothing to push, or a waterlogged tank making it start over and over — the box cuts the power before the damage lands, waits a spell, and tries again on its own timer. It is the ear test with no bedtime: it catches at 3am what you would have caught at 3pm.

The common models fit pumps from one-third horsepower up to five, work with both “2-wire” and “3-wire” setups — the same question you are already asking your well company — and run in the low hundreds of dollars, against the several thousand that a new pump and the crew to pull it will cost. Wiring it in happens inside the box, which on this site means one thing: a licensed electrician or your well company’s own tech does it, and for them it is a short visit. Checking that license takes five quiet minutes at the kitchen table — the AC soft starter page shows exactly how, and the same lookup works for every trade that knocks. See pump protection devices on Amazon.

And notice what you just bought. Storm week is the reason it goes on the wall — but a dry spell, a tired tank, or a bad day on the utility line can cook a pump in July with the grid working fine. The box does not know or care where the electricity came from. It just guards the pump, every day you own it.

The tank is your soft starter

The air conditioner has a $300 part that tames its surge. The well has something better, and you may already own it: the pressure tank. The bigger the tank's drawdown, the less often the pump starts — and starts are the whole problem. If your tank is small or waterlogged, the pump short-cycles: surge after surge after surge, each one a hit on the generator and a swallow of fuel. Ask your well company what your drawdown is. A larger tank is not a small purchase, but it pays twice — easier on the pump every day of the year, and easier on the generator the week you need it.

And the tank is not the well’s only trick. The $300 part from the air conditioner lesson has a cousin, and it is made for wells: soft-start devices built specifically for submersible well pumps — the common sizes cover half a horsepower up to three and a half — ease the motor up instead of slamming it, cutting the starting surge by roughly 60 to 70 percent, typically $300 to $600 installed. Same idea, same honest arithmetic: a few hundred dollars on the pump side can be thousands off the generator side. And the same warning travels with it — you want the device whose paperwork shows the starting current going down. While you have your well company on the phone about the drawdown, ask one more question: whether your pump is “2-wire” or “3-wire.” It decides where the pump’s starting parts live and which soft-start setup fits — and it is a question that makes you sound like you have done your homework, because you have.

One check before you spend anything, in the same spirit as the air conditioner page: some wells already have the gentle start built in. If your big blue tank was ever replaced by a little tank the size of a soccer ball, and your shower pressure holds rock-steady no matter how many faucets are open, you likely have a constant-pressure system — a pump that ramps up to match the water you are using instead of slamming on at full force. Those systems do not have the massive starting spike, which makes them friendlier to generators right out of the box. Know what you own before you size for a surge you may not have.

And the free version: fill everything before the storm. The bathtub for flushing, jugs for drinking, the big stock pot for the kitchen. Every gallon you store ahead of time is a pump start that never happens. On the hill where I grew up — a mountain community with one shared well and no repairman to call — everyone sized their water storage around how long pump parts took to arrive, back when a part meant a long-distance call and a drive down the mountain. You only need to size yours around a storm.

And a roughly $35 upgrade to the tub trick: a bathtub water bladder — a big food-safe bag that lines the tub before you fill it. Here is why it earns its keep: a bare tub carries soap film and dust, which is why we call tub water flushing water. The bag keeps the same hundred gallons clean enough to drink and cook with for weeks, it fills from the faucet in about twenty minutes, and it comes with a little hand pump so you draw off a jug at a time without lifting anything heavier than the jug — which past fifty is the whole point. Bare tub, flushing water. Bag in the tub, drinking water. For thirty-five dollars, that is a promotion worth buying — and it folds flat in a drawer the other 51 weeks of the year.

The Sump Pump — The Load That Picks Its Own Moment

A sump pump runs on about 800 watts and starts on roughly 2,400 — smaller numbers than the well, but with a nastier habit: it needs to run precisely when the weather is at its worst, which is precisely when the power fails. A generator that will be running anyway can carry it easily. The planning question is the hours when the generator is not running.

• A battery-backup sump pump is a second, smaller pump with its own battery, sitting in the same pit. (Some systems skip the second pump: a battery and a power box on the wall run your main pump when the grid quits — same insurance, one machine fewer.) It bridges the gap between the lights going out and the generator coming on — and covers the night, when nobody wants to go start an engine in the rain at 3am. Know what to expect from it: a full, healthy battery gives you roughly 5 to 7 hours of nonstop pumping, or one to three days of now-and-then pumping — and hard rain shortens that fast. A battery that lasts two days at a pump-every-five-minutes pace can be down to half a day when the pump runs every minute. One more quiet fact: the battery wears out in about three to five years even if it never runs once. Test it on the same April and October dates you test everything else, and put its birthday on the card in the panel door.
• A water-powered backup pump uses city water pressure to move sump water — no electricity at all. It only works if you are on municipal water, which makes it the rare storm product where being on city water is the advantage.
• Check the check valve. A failed check valve makes the pump re-lift the same water over and over — more starts, more surge, more fuel, for nothing. It is a ten-dollar part and a ten-minute look.

One sizing note for the calculator: if you checked both the well pump and the sump pump, remember that surge is not additive — the calculator sizes for the biggest single start, because motors do not agree to start in unison. But two automatic pumps do raise the odds that something is starting at any given moment, which is a good argument for the safety margin the calculator already builds in, and a bad argument for shaving it.

Do It at Fifty — While the Money and the Years Are Both on Your Side

Step back and look at what this page actually asked you to buy. A transfer switch. A soft start. A pump guard. Maybe a bigger tank. Every one of them is a hire-once purchase: quality equipment in this line runs fifteen to twenty-five years and often longer, and the wiring work behind it — the transfer switch, the inlet, the panel — is effectively done once in the life of the house. Do this at fifty and you are not buying a storm gadget. You are buying water that works through your entire retirement.

Now the part nobody likes to say out loud. At fifty, most of us are still cashing a working paycheck, and a fifteen-hundred-dollar job is a decision. At seventy-five, on a fixed check, that same job can be a door that does not open. The equipment does not care when you buy it. Your budget will.

And the price of waiting is not standing still. Every job on this page leans on licensed tradespeople, and the people who track the trades report the same story from every direction: for roughly every five tradespeople retiring, about two are coming up behind them, wages in the trades have been jumping by double digits in a single year, and the waits for good work keep getting longer. Whatever this work costs in your town today is likely the cheapest it will ever be. That is not a sales pitch. That is a calendar.

Which is the whole idea hiding in this website’s name. Prepare at fifty, while the money is working and the choosing is calm — and be the one at seventy-five whose water never blinked. The story behind the name is where that lesson was learned the first time.

And if the answer turns out to be a permanently installed standby unit rather than something you wheel out, get more than one quote and know what you are being quoted for before anybody walks the property. How to get generator quotes covers what to ask.