Buy a capacitor at a plumbing supply house, online retailer, or big-box hardware store

A well pump capacitor is a small electrical part that helps your pump motor start and run. When it fails, your pump won't turn on. You can buy a replacement at a local plumbing supply store (fastest if you need it today), from online retailers like Amazon or eBay, or from big-box stores like Home Depot or Lowe's. The part itself costs between $15 and $40 depending on the microfarad rating your pump needs.

The key is knowing what size capacitor your pump uses before you shop. That information is printed on the old capacitor itself or in your pump's manual. Buying the wrong size won't work and won't damage anything—it just won't start your pump. Buying the right one takes five minutes once you have the number.

Key Takeaways

  • Plumbing supply stores stock capacitors in common sizes and can often sell you one the same day you call.
  • The microfarad (µF) rating printed on your old capacitor is the only number you need to match when ordering a replacement.
  • Online retailers ship within two to five business days and often carry a wider range of sizes than local stores.
  • Home Depot and Lowe's carry capacitors in-store, but selection is smaller than at dedicated plumbing suppliers.

Plumbing supply stores: same-day pickup if you call ahead

A local plumbing supply house is the fastest route if you need the capacitor today. Call ahead with your pump's microfarad rating (the number on the old capacitor, like "30 µF" or "50 µF"), and they can tell you in one call whether they have it in stock. Most carry the common sizes—30, 35, 40, 50, and 60 microfarads—because residential wells use these ratings most often.

Plumbing supply stores also employ staff who understand well pumps. If you're unsure about the rating or have questions about installation, they can answer them. Prices are usually $20 to $35 for a standard capacitor. To find one near you, search "plumbing supply near me" or ask your well pump installer or service company for their supplier.

Online retailers: wider selection and lower prices

Amazon, eBay, and dedicated electrical supply sites like Grainger or Anixter carry capacitors in every microfarad size and often at lower prices than brick-and-mortar stores. Shipping takes two to five business days for standard delivery. The advantage is selection—if your pump uses an unusual size like 15 µF or 80 µF, online is often your only option.

When ordering online, search by the exact microfarad rating plus the word "capacitor" (for example, "50 µF well pump capacitor"). Read the product description to confirm it's rated for the voltage your pump uses—most residential well pumps run on 240 volts, but some older ones run on 110 volts. The listing should state the voltage clearly. Prices range from $12 to $30 depending on the brand and size.

Home Depot and Lowe's: in-store availability with limited selection

Both Home Depot and Lowe's stock capacitors in their electrical sections, and you can check availability online before you go. Selection is smaller than at plumbing suppliers—they typically carry 30, 40, and 50 microfarads in stock, but not the full range. Prices are competitive, usually $18 to $32.

The advantage is convenience if you're already shopping there or need the part the same day. The disadvantage is that staff in the electrical aisle may not be familiar with well pump capacitors specifically. If your pump uses an uncommon size, these stores may not have it and cannot order it for you—you'll need to go online or to a plumbing supplier.

Finding the right microfarad rating on your old capacitor

Before you shop anywhere, locate your old capacitor and read the number printed on its side. It will look like "30 µF", "50 µF", or "40 µF"—the µF stands for microfarad, which is the unit of electrical capacitance. This is the only number that matters. Write it down or take a photo of the capacitor with your phone.

If the old capacitor is damaged or the label is worn off, check your pump's manual or the nameplate on the pump motor itself. The manual often lists the capacitor size in the electrical specifications section. If you cannot find it, call your pump installer or a local well service company with your pump's brand and model number—they can tell you the correct size in one call.

Voltage rating: usually 240 volts for residential wells

Capacitors are also rated by voltage. Most residential well pumps use 240-volt capacitors, but some older pumps or shallow-well systems use 110 volts. The voltage rating is printed on the capacitor next to the microfarad number. When you order a replacement, match both the microfarad rating and the voltage.

If you buy a capacitor with the right microfarad rating but the wrong voltage, it will not work and you'll need to return it. Voltage is always listed in product descriptions online and on the package at physical stores, so check it before you buy. If you're unsure, ask the store staff or call the retailer before ordering.

Frequently Asked Questions

Can I use a capacitor with a higher microfarad rating than my pump needs?

No. Using a capacitor with a higher microfarad rating can damage your pump motor or cause it to overheat. Always match the exact microfarad number on your old capacitor. If you cannot find the exact size, contact the pump manufacturer or a well service company before buying a different one.

What if I can't find my pump's microfarad rating?

Check your pump's manual or the nameplate on the motor. If those aren't available, call your well pump installer or a local well service company with your pump's brand and model. They can tell you the correct size. You can also take a photo of your pump and bring it to a plumbing supply store—staff there can often identify the size by looking at the pump.

How long does a capacitor last?

Most capacitors last five to ten years, though some fail sooner in hot climates or if the pump runs frequently. When a capacitor fails, the pump will not start. Replacing it is inexpensive and straightforward—the part costs $15 to $40 and installation takes a few minutes if you're comfortable with electrical connections.

Is it safe to replace the capacitor myself?

Capacitors store electrical charge even when power is off, so discharge the old one before touching it. Wear rubber gloves and use an insulated screwdriver to short the terminals together. If you're not comfortable working with electrical parts, hire a well service technician—the labor cost is usually $100 to $200, but the work is quick.

Do I need to turn off power before replacing the capacitor?

Yes. Switch off the breaker that controls your well pump before you touch anything. Wait a few minutes, then discharge the old capacitor by shorting its terminals with an insulated screwdriver. This removes any stored charge and prevents electrical shock.