If you’ve ever relied on a self-priming pump for moving water in agricultural irrigation, residential wastewater systems, or small-scale industrial fluid transfer, you know how frustrating it is when it suddenly loses efficiency mid-job. Last month, I got a call from a regular customer of mine—they’ve used our self-priming pumps for 5 years to circulate water through their community garden’s drip irrigation lines—saying theirs stopped priming properly. When I asked if they’d skipped a recent cleaning, they admitted they’d only checked the inlet strainer once in the last growing season. That’s a mistake I see far too often: self-priming pumps require regular, intentional cleaning to keep running at peak performance, and as a supplier who’s worked with these pumps day in and day out for 12 years, I’ve learned that skipping this step doesn’t just lead to bad flow—it can shorten a pump’s lifespan by years. Self-Priming Pump
Today, I’m walking you through a step-by-step, scientifically sound process for cleaning a self-priming pump, plus the small, regular maintenance habits that’ll keep yours from acting like my customer’s did. I’m not here to sell you something you don’t need, but when you’re a pump supplier, you see exactly what happens when people cut corners on cleaning—so this advice is rooted in both manufacturer specs and real-world fixes that work. Let’s start with why self-priming pumps are different from standard centrifugal pumps, because that’s the first thing most people get wrong when cleaning them.
A standard centrifugal pump needs to be fully submerged in fluid to prime, right? But a self-priming pump has a built-in prime chamber that traps a small amount of fluid inside itself after the first start-up, which lets it pull fluid from a source that’s below the pump’s elevation. That prime chamber is the heart of the self-priming function—and it’s also the spot where gunk, sediment, and trapped air build up, which is why cleaning it is non-negotiable. If you ignore that chamber, sediment will scratch the impeller’s fins, trapped air will prevent the pump from pulling fluid, and mineral deposits from hard water will clog the small passages that make the priming process work.
First, let’s cover when you should clean your pump. I recommend a full deep clean every 3 to 6 months, depending on how often you use it and the fluid it’s moving. For pumps used in agricultural settings, construction sites, or systems that move muddy water or wastewater, that timeline drops to every 2 to 3 months. For residential pumps moving clean well water or clear pool water, once every 6 months is fine. You should also do a quick pre-use check (5 minutes) before every start-up: that means looking at the inlet strainer to make sure it’s not clogged with leaves or debris, and checking that the prime port cap is tight (loose caps let air in, which kills priming). If you notice the pump’s flow is weaker than usual, or it’s making a high-pitched whirring noise instead of a steady hum when it runs, that’s your signal to do a full clean right away—don’t wait for it to stop working entirely.
Now, let’s get to the actual cleaning process. I’ve tested this on every type of self-priming pump we supply, from 1/2 horsepower residential models to 5 horsepower industrial units, and it works across the board. First, safety first: always disconnect the pump’s power source before you do any work. No exceptions. I’ve seen too many near-misses where someone forgot to unplug the pump and it turned on mid-clean, which can lead to serious injury. If you’re working with a pump that’s been running recently, let it cool down for 30 minutes too—pump casings get hot, and you don’t want to burn your hands.
Next, prepare the work area. You’re going to be draining fluid and pulling apart parts, so lay down old rags or a plastic tarp to catch spills, especially if you’re working with wastewater or water with sediment. Have on hand: a Phillips head screwdriver, a flathead screwdriver, a bucket for draining fluid, a soft-bristled brush (a toothbrush works for small parts, a dish brush for larger casings), a mild, non-abrasive detergent (dish soap is fine—avoid anything with bleach, as it can damage pump seals), and clean water for rinsing. If you have a pump that moves fluid with oil or chemicals, check the manufacturer’s specs for a specialized cleaner, but for most water-based applications, dish soap works perfectly.
Step 1: Drain the remaining fluid from the pump’s prime chamber. Most self-priming pumps have a drain plug on the bottom of the pump casing, right below the prime chamber. Loosen that plug with a wrench, and let all the old fluid—along with any sediment that’s settled—drain into your bucket. While you’re at it, remove the inlet strainer (it’s at the end of the suction pipe, usually a plastic or metal mesh basket) and rinse it with clean water to remove debris. If the strainer is really clogged, you can soak it in warm soapy water for 10 minutes first, then scrub it with a soft brush to get rid of built-up gunk. Never use a wire brush on the strainer— it can scratch the mesh and let small debris pass through, which will damage the pump later.
Step 2: Disassemble the pump casing to access the prime chamber and impeller. This is where most people hesitate, but it’s simpler than it sounds. Remove the four or six bolts that hold the pump casing together (the number depends on the pump size) with your Phillips or flathead screwdriver. Carefully separate the two halves of the casing—you’ll see the impeller, a small fan-shaped wheel, inside, and the prime chamber, the curved space that wraps around it. Set the bolts aside in a small container so you don’t lose them; I’ve learned the hard way that losing one bolt mid-clean means waiting days to get a replacement, and that’s costly when you’re relying on the pump for irrigation or other critical tasks.
Step 3: Clean the prime chamber and impeller. This is the most important part, because this is where the majority of buildup happens. First, inspect the impeller: look for any caked-on sediment, mineral deposits, or debris wrapped around its fins. If it’s small enough to fit in your hand, you can hold it under running water and gently scrub it with your soft brush and a drop of dish soap. For stubborn mineral deposits (common in hard water areas), you can soak the impeller in a 50/50 mix of warm water and white vinegar for 15 minutes before scrubbing—vinegar dissolves mineral buildup without damaging the plastic or metal of the impeller. Don’t use anything sharp to scrape the impeller, though—scratches on the impeller’s fins will throw off its balance, making the pump vibrate and wear out faster over time. Next, clean the prime chamber: use your soft brush and soapy water to scrub all the inner surfaces of the casing, paying extra attention to the small passageways that connect the chamber to the inlet and outlet ports. These passages are tiny, and even a small piece of sediment can block them, which will prevent the pump from priming correctly. If you notice any built-up grime in these small spots, use an old toothpick (be gentle so you don’t break the plastic) to dislodge it, then rinse thoroughly.
Step 4: Inspect and clean the seals and O-rings. This is another part that’s easy to miss, but critical. Around the edge of the pump casing halves, and around the shaft where the impeller connects to the motor, there are rubber O-rings and seals that prevent fluid from leaking out of the pump. Pull these out gently (they’re usually slightly seated in grooves) and check for cracks, tears, or signs of wear. If an O-ring is damaged, replace it before putting the pump back together—leaks from a damaged seal can let air into the system, which will kill the pump’s priming ability. If the O-rings just have a little dirt on them, you can clean them with a soft cloth and soapy water, then lightly lubricate them with food-grade silicone grease (never use petroleum jelly, which can break down rubber over time) to make reassembly easier.
Step 5: Rinse all parts thoroughly and reassemble the pump. Once you’ve cleaned the impeller, prime chamber, strainer, and O-rings, rinse every part with clean water to remove all soap or vinegar residue—any leftover cleaner can damage pump seals or contaminate the fluid you’re moving later. Let all parts air dry for 10 minutes (don’t use a rag to dry them, in case there’s lint left behind). Now, put the pump back together: line up the casing halves, tighten the bolts in a crisscross pattern (this ensures even pressure and prevents leaks—don’t just tighten one bolt all the way at a time), replace the O-rings, put the inlet strainer back on, and tighten the drain plug. Don’t over-tighten any bolts—this can crack the pump casing, which will lead to leaks.
Step 6: Prime the test the pump before putting it back into service. This is the final, make-or-break step. Fill the prime chamber completely with clean water (most pumps have a fill port on the top of the casing—just remove the cap and pour water in until it starts coming out the outlet port), then make sure the prime port cap is tight. Reconnect the power, and run the pump for 30 seconds while monitoring the flow. If you see steady, strong flow coming out, you’re good to go. If it’s sputtering or not priming, double-check that all bolts are tightened evenly, that there’s no air leaks in the inlet line, and that you didn’t leave any debris blocking the impeller or prime chamber.
Now, a few long-term maintenance tips that’ll cut down on how often you need to do deep cleans. First, install a pre-filter on the pump’s inlet line—this catches large debris before it even reaches the strainer, so the strainer doesn’t clog as fast. Second, if you’re storing the pump for an extended period (like over winter for an agricultural irrigation system), drain all fluid completely, disassemble the pump, clean all parts, and store it in a dry, cool place. Leaving fluid in the pump over winter leads to mineral buildup and even rust, which will make the next start-up way harder. Third, if you move non-potable fluid (like wastewater or construction slurry), add a secondary strainer to catch fine sediment—this will protect the impeller and prime chamber from abrasive particles that cause wear over time.
I get questions all the time: “Do I really need to do all this, or can I just wipe the outside?” The answer is no, because the inside of the pump is where the work happens. A customer of mine in Arizona once told me he skipped cleaning his pump for two years, and it cost him a new impeller (which is a $150 part, not to mention the downtime of his farm’s irrigation system) when sediment scratched the fins so bad it couldn’t create the vacuum needed to prime. Another customer used a wire brush to clean the impeller, and the scratches threw the pump’s balance off, leading to a broken shaft that cost $400 to replace. These are avoidable mistakes, and that’s why taking the time to clean the pump properly is worth every minute.
At the end of the day, a self-priming pump is only as good as the care you put into it. Whether you’re using a small residential pump for a backyard pond or a large industrial unit for a construction site, regular cleaning will extend its lifespan, improve efficiency, and save you from costly breakdowns. If you have questions specific to your pump model, or you need replacement parts like O-rings or strainers, don’t hesitate to reach out. I’ve worked with hundreds of customers to troubleshoot pump issues, and I’m happy to help you get your system running smoothly. If you’re looking to upgrade to a new self-priming pump or discuss maintenance plans for your current setup, contact our team to connect with a specialist who can tailor advice to your needs.
High Flow Stainless Deep Well Pump REFERENCES
- Hydraulic Institute. (2020). Self-Priming Pump Maintenance Guidelines. Hydraulic Standards for Centrifugal Pumps, 12th Edition.
- American Society of Agricultural and Biological Engineers (ASABE). (2019). Maintenance of Irrigation Pumps for Agricultural Applications. ASABE EP405.1.
- Pump Industry Association. (2021). Best Practices for Pump Cleaning and Storage in Residential and Light Commercial Applications. PIA Technical Bulletin 107.
Longbiao Pump Industry Co., Ltd.
We are one of the most professional self-priming pump manufacturers and suppliers in China, featured by quality products and low price. Please rest assured to buy discount self-priming pump for sale here from our factory. We also accept customized orders.
Address: Unit 101, Building 11, Pan’ao Entrepreneurship Park, Daxi Town, Wenling City, Taizhou City, Zhejiang Province, P.R. China
E-mail: 1653746797@qq.com
WebSite: https://www.cnlongbiao.com/
