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Backflow Prevention and Testing Across Hawaii

Fast, reliable service, done right the first time.

Backflow preventer installation, testing and repair on Oahu, Maui and the Big Island to keep dirty water out of the clean water you drink.

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Backflow happens when water reverses direction and moves from your plumbing, irrigation or another source back into the clean supply. It is not something you can see, which is why it is easy to ignore until there is a problem. All Aloha Plumbing installs, tests and repairs backflow prevention devices for homes and businesses on Oahu, Maui and the Big Island. We are family-owned, licensed and insured, and we hold Hawaii contractor license CT-36812.

How Backflow Happens

There are two main causes. Back pressure occurs when pressure on your side of the system, such as from a pump, boiler or elevated tank, rises above the pressure in the supply line and pushes water the wrong way. Back siphonage occurs when supply pressure drops, for example during a water main break or heavy draw nearby, and pulls water backward like a straw.

Either one can draw water from a garden hose, irrigation line, pool fill or process equipment into the lines that feed your kitchen, bathroom and laundry. That water can carry bacteria, fertilizer, chemicals or other contaminants.

A backflow preventer is the barrier between those sources and your drinking water. Without one, or with a device that has worn out, a single pressure change can be enough to pull contaminated water into the lines your family uses every day.

Devices We Install and Test

The right device depends on the hazard. Common options include:

  • Hose bib vacuum breakers on outdoor faucets
  • Pressure vacuum breakers on many lawn irrigation systems
  • Double check valve assemblies for lower-hazard connections
  • Reduced pressure zone assemblies for higher-hazard connections, often at commercial sites
  • Air gaps, the simplest protection, where a physical space separates the outlet from the water it fills

Testable assemblies have valves and test ports that let us confirm the checks hold and the relief valve opens when it should. If a device fails, we repair or replace the worn parts, or replace the assembly. Your water utility may require periodic testing of certain devices, and new installations may require a permit.

Backflow Concerns by Island

  • Oahu: Our team works from Waipahu across Honolulu, Kapolei, Ewa Beach, Pearl City, Mililani and Kaneohe. Commercial buildings, high-rises with booster pumps and homes with irrigation are common sources of back pressure. See backflow prevention on Oahu.
  • Maui: From Makawao, we serve Kahului, Wailuku, Kihei, Lahaina, Wailea and Upcountry. Resorts, vacation rentals and larger irrigated lots in South and West Maui often rely on these assemblies. Near the coast, salt air corrodes exposed brass and bronze bodies faster, so outdoor devices deserve regular checks. See backflow prevention on Maui.
  • Big Island: We serve Kailua-Kona, Hilo, Waimea, Waikoloa and Pahoa. Properties that use both rainwater catchment and county water need the two kept apart so untreated catchment water cannot enter the public supply. Arrival windows vary because the island is large. See backflow prevention on the Big Island.

Signs You May Have a Problem

  • Discolored, cloudy or bad-smelling water from the tap
  • Water dripping or spraying from a backflow assembly relief valve
  • A test notice from your water utility
  • New irrigation, a pool, a pump or commercial equipment tied into your water line

If the water looks or smells wrong, stop drinking it until the cause is found. You get upfront pricing that you approve before we start, and financing plus senior and military discounts are available.

For local details, choose your island page above. For anything urgent, call the number at the top of this page and a real plumber will answer, 24/7.

Need Backflow Prevention on Hawaii?

A real plumber answers 24/7. Average island response: under 30 minutes.

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Need Help Now?

Plumbers on call 24/7 across Oahu, Maui,
and the Big Island.

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Quick Answers

Good To Know

Do you test and install backflow devices on all three islands?

Yes. All Aloha Plumbing installs, tests and repairs backflow prevention devices on Oahu, Maui and the Big Island. That includes residential irrigation and hose connections as well as commercial assemblies. Each island page has local details and a way to request service in your area.

What does a backflow preventer actually do?

It lets water flow one way only, from the supply into your property. Inside are spring-loaded check valves, and on some models a relief valve, that close or open when pressure changes would otherwise push or pull water backward. That keeps irrigation, pool or process water from reaching the lines you drink from.

How often should a backflow assembly be tested?

It depends on the device and on your water utility. Testable assemblies are usually checked on a regular schedule, and your utility may send a notice when a test is due. Devices outdoors near the coast can wear faster from salt air. We can test your assembly and let you know if any parts need repair.

Why does backflow matter for homes with catchment?

Rainwater catchment water is not treated the same way as county water. If a home is connected to both, a cross connection could let catchment water flow back into the public line. A proper backflow device or air gap keeps the two separate. This is more common on the Big Island and in rural parts of Maui.

Real Customers • Real Stories

What Our Ohana Says

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“All Aloha came out super fast and fixed our leak the same day. Excellent service! These guys are real pros and treated my home with respect.”

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“They replaced our water heater quickly and left everything spotless. The crew showed up exactly when they said they would. Couldn’t ask for better.”

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Kailua, Oahu

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“Called at midnight with a burst pipe. They were here in 25 minutes and had it contained before the ceiling came down.”

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Kapolei, Oahu

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Proudly Serving

Three Islands. One Family.

From the North Shore to Hilo, we’re proud to bring honest plumbing with aloha to homes across Hawaii.

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Maui

Maui

Kahului • Lahaina • Kihei • Wailuku

Oahu

Oahu

Honolulu • North Shore • Kailua

Big Island

Big Island

Kailua-Kona • Hilo • Waimea

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