Well pump replacement around Knoxville

Once a licensed installer has confirmed the pump itself is done, the replacement is mostly about getting the next one right. The pump that came with the house may not have been sized well in the first place, and a household with more people or more bathrooms than it had twenty years ago may need something different. Here is what goes into the job and what to ask.

How the new pump gets picked

TDEC lists the numbers an installer works from when choosing a pump: the casing diameter, how deep the well is, the static water level, how much the well yields, how far the water level draws down while pumping, the vertical lift to the house, friction loss in the pipe, and how many fixtures or people the system serves. Most of that is written on the driller's report for your well. If you don't have a copy, TDEC's records can often supply it (see well depths and records).

The well's yield sets a ceiling on what any pump can deliver. TDEC's guidance is that a well producing 3 to 5 gallons a minute or more will usually serve a household of four to six. State records show a quarter of the home wells drilled in Union County reported less than 3 gallons a minute, so on some lots the right answer is a smaller pump with more storage rather than a bigger pump.

What the job looks like

• Pulling the old pump. The drop pipe, wire and pump come up through the pitless adapter. On a 300- or 400-foot well, that is a lot of pipe to lift and lay out.
• Inspecting what comes up. Splices, wire insulation, the check valve and the pipe joints all get checked. Corroded or damaged pieces get replaced while everything is out.
• Setting the new pump at the right depth. Far enough below the pumping water level to stay submerged in a dry season, and clear of the bottom.
• Wiring to code. Tennessee's well standards require installation to the National Electrical Code, grounding from the motor frame to the service entrance, and a ground to steel casing above the surface. Submersible pump cable can't be buried bare: TDEC says it goes in conduit 18 inches down, while UF or USE cable can be buried directly at 24 inches.
• Checking the tank and switch. A new pump paired with a waterlogged tank will short-cycle itself to death. See pressure tank replacement.
• Disinfecting the well. TDEC's method is one gallon of bleach for every 50 feet of well depth, run to each faucet until you smell chlorine, left at least 12 hours, then pumped out until the smell is gone. TDEC also says not to run that heavily chlorinated water through a septic system. The installer should handle this or tell you how.

Constant-pressure systems

Some installers offer a variable-speed (VFD) controller that speeds the pump up or down to hold steady pressure, instead of the usual on-off cycle. Nebraska Extension notes these systems usually start the pump fewer times but rely on sensitive electronics, so pick an installer who has worked on them and keep the manual.

Questions to ask before work starts

TDEC suggests asking any driller or pump installer for a written contract, proof of insurance, the license certificate and references, and an itemized price. On a pump job, also ask:

• What pump, what horsepower, and at what depth will it be set?
• Is new wire or drop pipe included, or priced separately if needed?
• Is the pressure tank being checked or replaced?
• Does the price include disinfecting the well?
• What warranty comes with the pump, and does labor have one too?

Prices vary with depth, pump size and what else needs replacing, so get the number from the installer before they start.

Good questions

How long does a well pump replacement take?

It depends on depth, access to the wellhead and whether anything else needs replacing. Ask the installer when they quote the job; we don't promise times.

Should I test my water after a new pump goes in?

Yes. EPA advises testing a private well right away whenever any part of the well system is repaired or replaced, once the disinfection chlorine has been flushed out.

Will a bigger pump give me more water?

Not if the well itself can't keep up. A pump can only move what the well yields; oversizing it can draw the water down to the intake. Storage and the right setting depth often matter more.