Frequently Asked Questions

FAQ Regarding Water Hardness

For water quality data for non-regulated parameters, such as pH, alkalinity, hardness, and conductivity, are provided on SPU's website at:


                      How do we know High-Density Polyethylene Pipe (HDPE) is safe to use for Drinking Water?

What is HDPE pipe?

High-Density Polyethylene or HDPE pipe is a commonly produced, flexible plastic pipe made of thermoplastic high-density polyethylene widely used for low-temperature fluid and gas transfer. The strong molecular bond of HDPE pipe materials helps it to be used for high-pressure pipelines. HDPE plastic is one of the most versatile of plastics—used in everything from hard hats to house wraps—it's also widely recycled, in both its rigid form (e.g., containers), and flexible form (e.g., polybags). Polyethylene pipes have a long and distinguished service history for gas, oil, mining, water, and other industries. Due to the low weight and high corrosion resistance of HDPE pipes, the industry is growing tremendously.

What is HDPE made from?

HDPE pipes are made by the polymerization of ethylene, a by-product of oil. Various additives (stabilizers, fillers, plasticizers, softeners, lubricants, colorants, flame retardants, blowing agents, crosslinking agents, ultraviolet degradable additives, etc.) are added to produce the final HDPE pipe and components.

What is the history of HDPE pipe use?

In the year 1953, Karl Ziegler and Erhard Holzkamp discovered high-density polyethylene (HDPE). Solid-wall HDPE pipes began replacing metal pipes in oil and gas systems in the late 1950s. In the early 1960s, gas utilities started replacing failing iron pipes with HDPE pipes, and because of its success, 95% of all new gas distribution systems installed today use HDPE. Soon after, HDPE pipes began to be used in agricultural drainage systems. In the 1980s, HDPE began to replace metal and concrete in stormwater culverts. HDPE is the insulation coating on the overhead telephone and electrical lines. HDPE is the same substance used in bottle caps, reusable water bottles, plastic lumber, patio furniture, hula hoops…the list goes on and on.

Is HDPE pipe considered “Food Safe”?

HDPE pipe is a common industrial plastic that is highly utilized in modern applications. Federal Regulation oversees the use and service of HDPE. The FDA considers HDPE pipe to be “approved food grade - BPA Free” (aka ANSI/NSI 61) and is approved for potable water applications. The molecules of HDPE are more tightly packed and stable than other food-grade plastics, meaning less plastic can leach into your food. The safest food-grade containers/buckets made from HDPE have the #2 symbol stamped on them, which indicates the plastic is considered safe from any BPA leakage. There has been no evidence of any widespread health problems associated with the use of HDPE in food and beverage or drinking water applications.

Will Sunlight affect HDPE pipe?

Sunlight contains ultraviolet rays that reduce the tensile properties of plastics with time. Usually, 3-5% carbon black is added to HDPE to make it UV resistant, which turns HDPE pipes black in color. HDPE pipe is installed in the ground, covered with at least 18” of ground cover, and not subjected to UV rays. This UV protection allows HDPE to be used in telephone and electrical wires that are consistently exposed to UV light, without any loss of tensile strength.

Will gasoline or wildfire affect HDPE pipes?

Gasoline does not adversely affect HDPE. The material does not soften or lose strength when exposed to gasoline. However, HDPE pipes will burn if exposed to an outside fuel source (i.e., gasoline). This could happen if there was a large fuel spill adjacent to the pipe. However, the fire would extinguish itself quickly due to the lack of an air supply and the fact that the pipe is buried.

Why did we choose HDPE pipe?

• The durability of HDPE is one of the benefits of HDPE. It has 100+ years of useful life.

• HDPE saves money because it is inexpensive compared to ductile iron pipe or copper. Currently, HDPE is less than half the cost of Ductile Iron Pipe.

• HDPE is superior to metals. It is lighter, flexible, and doesn’t fracture due to freezing.

• HDPE is efficient to produce. It requires less energy to fabricate, transport, and install than metal alternatives.

• HDPE won’t rust or fracture. It is resistant to corrosion and scaling.

• HDPE is rigid enough to hold its form over time, even in a seismically active area, and it is flexible enough to bend around corners and under creeks or streams.

• Installation of HDPE pipe is often “trenchless,” meaning that the new pipe can be pulled through the old pipe, and the road does not have to be “open cut.”

• 20-foot sections are joined using butt fusion, making a longer section of pipe that is effectively seamless.

• The seamless HDPE pipe is essentially leakproof and has a longer life than ductile iron pipe because there are no joints to slip or allow root intrusion.

• HDPE is better for our employees, too. It’s so light, one person can carry a 20- foot section, and it won’t break or hurt someone’s foot if it’s dropped!

• Using flexible HDPE typically means no ugly trenches or damaged driveways, streets, sidewalks, or landscaping. 

• Best of all, replacing old mains with HDPE saves you money! The design, purchase, and installation of HDPE are significantly more affordable than Ductile-Iron pipes. This means your water rates go further.

What about microplastics? Will using HDPE pipe cause me to be exposed to microplastics in my drinking water?

Microplastics are plastic pieces between one micrometer (one-millionth of a meter) and five millimeters in size. Nanoplastics are even smaller than one micrometer. 35% of all microplastics come from synthetic fibers (i.e., fleece) released during clothes-washing. Another 30% comes from car tires. Plastic breaks down over time, especially when exposed to the atmosphere and UV light for long periods of time. HDPE pipe is protected from breakdown by the black carbon that blocks UV light and the fact that the pipe is buried and not exposed to the atmosphere.

Wait, I have heard about plastic pipes before, don’t they break easily?

The polyvinyl Chloride (PVC) pipe material introduced in the 1970s led to an unacceptable leakage rate. This type of pipe was prone to splitting and is not the same as the HDPE plastic pipe we use today.

Is there a situation where HDPE pipe is not a good choice?

HDPE pipes can work satisfactorily in a wide temperature range of -220 F to +180 F. However, the use of HDPE Pipes is not suggested when the fluid temperature exceeds 122 F (50 C).

Would you like more information on Trenchless Installation of HDPE?

Check out these videos:

Information for this FAQ has been collected from these resources:


The Plastics Paradox, Facts for a Brighter Future, Chris DeArmitt, PHD


What is the District's Policy on ADUs?


Accessory Dwelling Units (ADUs) offer a way to include smaller, affordable homes in 
established neighborhoods. These give homeowners the flexibility to share independent living areas with family members and others while maintaining privacy, including but not limited to allowing seniors to age in place as they require more care, helping extended families to be near one another, and providing rental income. ADUs help to address housing shortages by increasing supply in single-family neighborhoods and providing an affordable place to rent. The benefits that ADUs offer have made them increasingly popular. 

The purpose of this Accessory Dwelling Unit (ADU) Policy is to formally address ADU fees and charges and provide additional requirements for these dwellings as they pertain to water improvements. To the extent the requirements contained in this Policy differ from or conflict with the District Standards and Details, this document shall control. 

An ADU in King County Water District No. 90 (District) must be lawful and permitted 
through the agency having land use permitting authority. For the District, this would be the City of Renton or King County. It is not the purpose of this policy to regulate land use within the authority of other local jurisdictions but rather to provide rules and regulations limited to the jurisdictional authority provided to Water and Sewer Districts pursuant to Chapter 57.08 RCW. This policy and the rules and regulations contained herein should be read within that context.


Accessory Dwelling Unit (ADU) - An ADU is defined as an accessory dwelling unit that is either attached to the primary single-family dwelling unit (AADU) or is a detached 
accessory dwelling unit (DADU) that is located on the same residential parcel as the 
primary residence. An ADU is a habitable single-family dwelling unit that provides basic living, sleeping, eating, cooking, and sanitation requirements.

Attached Accessory Dwelling Unit (AADU) – An AADU is an ADU that is physically
attached to the primary single-family dwelling unit.

Detached Accessory Dwelling Unit (DADU) – A DADU is an ADU that consists partly or entirely of a building that is separate and physically detached from the primary single family dwelling unit. Examples would include, but not be limited to, tiny houses, backyard cottages, or converted outbuildings.

Equivalent Residential Unit (ERU) - The term used for the typical amount of water a single family residence uses over the course of a day. 

Single-Family Dwelling Unit – A detached single-family structure containing one dwelling unit, commonly known as a house.


The meter serving an ADU (DADU or AADU) may be shared with the primary single-family residence or separately serve the ADU.

Existing Meter – ADUs can be served by the existing service line and meter from the District’s water main. Customers with ADUs will be charged a double-use rate. (Two times the Base Rate and two times the Consumption Tiers.) Property Owners with an ADU can purchase a “deduct” meter if they desire to know and/or bill the water for the ADU separately. The deduct meter will be purchased by, and belong to, the Property Owner. The District will not perform maintenance, meter readings, or billing on a deduct meter. 

Every ADU created after November 30, 2023 must be served by at least a 1-inch service line from the water main to the meter, along with a 1-inch meter to serve an ADU and the Primary Residence. A larger service line and/or meter is only required if necessary to serve the ADU adequately. If the Property Owner proposes to serve the ADU with an existing meter and the District determines that the meter is insufficient to do so, the Property Owner must upsize the meter. 

Separate Service and Meter -  Pursuant to HB1337 passed on April 6, 2023, “A city or county may not prohibit the sale or other conveyance of a condominium unit independently of a principal unit solely on the grounds that the condominium unit was originally built as an accessory dwelling unit.”

HB 1337 allows Property Owners to sell an ADU as a separate lot. The primary residence and the ADU cannot be sold separately unless the City of Renton or King County allows the parcel to be split. For this reason, ADUs built after April 2023 should have a separate meter connection for the ADU and will pay the full installation and fees to have a separate meter installed. The service line from the Meter to the ADU is the property owner’s responsibility. The connection charges below (#4) are due when a separate service connection is installed. Property Owners who do not have a separate service connection will have a notice placed on their property title clearly stating that a separate service connection is required to be installed before an ADU is sold as a separate dwelling. Any legal fees and recording costs will be charged to the property owner. The charge for a future separate service line and 
meter will be based on the District’s Schedule of Charges applicable at the time the service is installed. 


ADUs (DADU & AADU) at or under 1,000 square feet will be assessed a General Facility Charge (GFC) that is based on one Equivalent Residential Units (ERU) for water where applicable. 

The cost of the meter installation, either a “Meter Drop” or a “Full Install,” must be paid to the District before the new meter is installed. Meter Drop and Full Install rates are included in the District’s current Schedule of Charges. Additionally, The Seattle Public Utilities Facility Charge (aka Conservation Fee) must be paid at the current single-family rate. All fees are due at the time of meter purchase and/or meter upsize.


The District supports the State’s housing goals as defined in Engrossed House Bill 
1337. The goal of the bill is to “expand housing options by easing barriers to the 
construction and use of accessory dwelling units.” Additionally, the bill states, “The 
legislature intends to promote and encourage the creation of accessory dwelling 
units as a means to address the need for additional affordable housing.”
Section 5 of HB 1337 states, “Cities and Counties may only offer such reduced or 
deferred fees, deferred taxes, waivers, or other incentives for the development or 
construction of accessory dwelling units if: 

1) The units are located within an urban growth area; and

2) The units are subject to a program adopted by the city or county with 
effective binding commitments or covenants that the units will be 
primarily used for long-term housing consistent with the public purpose 
for this authorization.”

To support the State’s goals of creating more low-income housing, ADUs meeting 
these conditions are eligible for a 15% reduction on the District’s General Facility 
Charge. All other fees (permits, meter installation, paving, etc.) are the same rate 
as a single-family home. 

Once approval of an ADU is provided by King County or the City of Renton (i.e.,
construction permit), the Property Owner must complete a Water Availability Application in advance of construction to ensure sufficient water is available to the property. Additionally, the property owner is responsible for informing the District when the ADU is ready to be connected to the original service line/meter or when a separate meter and service line are ready to be installed. District staff will install the service line from the main to the meter along with a new meter. The property owner is responsible for installing the service line from the meter to the ADU.

Bimonthly billing will begin for an ADU once a new meter or new connection is made.
Additional fees for permits, inspections, road restoration, and additional staff time will be charged to the property owner. All known fees must be paid in advance of the meter installation. Occasionally, charges for additional staff time and road repair are not known until after the work is completed. Additional charges are due 30 days after being invoiced.

Failure to inform the District that an ADU has been connected to the District Water System will not stop bi-monthly base rate and consumption charges being applied retroactively to the date of connection.

How do I start a new service?

To start a new service, you have three options:

  1. Complete our online form
  2. Email us at
  3. Call the District office at 425-255-9600

We prefer to have the online form filled out so we have your complete information and correct spellings and will set up your account based on the information you provide.

Regarding Current Lead Issue

What is the Pink Residue in my Bathroom?

Please click to open the form

Each year, a few Water District No. 90 customers call to ask about a slimy pink substance that sometimes forms in moist areas around their homes. They most frequently observe it in toilet bowls, on the surfaces in shower stalls, bathtub enclosures, in sinks, and in pet water dishes.

Red or pink-pigmented bacteria known as Serratia marcescens is thought to be the cause of the pink stuff. Serratia bacteria are common inhabitants of our environment and can be found in many places, including human and animal feces, dust, soil, and in surface water. The bacteria will grow in any moist location where phosphorous containing-materials or fatty substances accumulate. Sources of these substances include soap residues in bathing areas, feces in toilets, and soap and food residues in pet water dishes. Serratia can also grow in tap water in locations such as toilets in guest bathrooms where the water is left standing long enough for the chlorine residual disinfectant to dissipate. Serratia marsescens is not known to cause any waterborne diseases.

Once established, the organism usually cannot be eliminated. However, periodic and thorough cleaning of the surfaces where the pink slime occurs, followed by disinfection with chlorine bleach appear to be the best way to control it. Scrub the surfaces where phosphorus and fatty substances, or the bacteria accumulate with a brush and a household cleanser. Then disinfect the surfaces where the slime has formed with a strong chlorine bleach solution. Leave the disinfectant solution on the affected surfaces(s) for 10-20 minutes before thoroughly rinsing it away with clean water.

To control “pink stuff” in toilets, clean the bowl thoroughly and spray chlorine bleach into the bowl and under the bowl rim. Also, add ¼ cup of bleach to the toilet tank. Let the bleach stand for 15-20 minutes. After 15-20 minutes, flush the toilet a couple of times to rinse the disinfectant out of the tank and the bowl.


Bleach should not be left in the toilet tank for prolonged periods; it will damage the rubber valves and seals inside. Whenever a pink film starts to reappear, repeat the cleaning and disinfection process.

If you have further questions, contact our office at 425-255-9600 or email

FAQ Boil Order

How do I contact the District?


15606 S.E. 128th Street
Renton, Washington 98059

Office Hours:

Monday through Thursday, 8:00 A.M. to 4:30 P.M.

Friday available by phone or email 8 AM to 4:30 PM. Office closed for walk-in.

Phone Number: (425) 255-9600

Fax Number: (425) 277-4128

Email: info@KCWD90.COM

How can I turn off the water in an emergency?

All homes should have a shut-off valve located at the residence. However, if your home does not have one, you may (in an emergency), turn the water off at the water meter. Meters are generally located at the front of the property, near the road. The recommended tools to have on hand are a crescent wrench and/or a meter wrench which can be purchased at your local hardware store (approximately $15.00). Firstly, locate the valve (silver dollar-sized, brass-colored with a raised bar in the center). Place the wrench over the raised bar and turn it to the right until the “eyes” on the valve are aligned. Repair leak(s) and reverse the process to re-establish water service to the residence.

Can I turn my water back on myself?

Meters are maintained by the District, but in emergency situations, it is advantageous that the homeowner turn the water on/off. When turning the water back on, reverse the steps in the "How can I turn my water off in an emergency?" FAQ section. Turn the raised bar only ¼ turn counter-clockwise to bring the water back into the system slowly. Then open the valve all the way.

Can my water be shut off in a District emergency and will I be notified?

Yes. In the event that there is a planned shut down, the affected customers will be notified prior to the shut down. For customer convenience, our field crew will leave a door tag with the date and estimated down time. However, in the event of such a shutdown, customers should make sure that they do not operate dishwashers, washing machines and showers during the shut down period. However, there may be critical circumstances which would result in an unplanned shut down (e.g., an accident, main break, etc.). In this situation, there would be no notification to our customers. The main focus would be to repair and/or restore water service as quickly as possible with a minimum impact to our affected customers. Please note that customers can call our main phone number 24-hours-a-day for information and/or to report an emergency.

Does the water contain Fluoride?

Yes. The range of fluoride for all of the District’s water sources is between 0.8 and 1.2 parts per million (ppm). The average is 0.8 ppm. The EPA’s maximum allowable limit is 4.0 ppm.

How do I know the District's water is safe?

The District is committed to providing residents with a safe and reliable supply of high quality drinking water. SPU and private laboratories tests our water regularly using sophisticated equipment and state of the art procedures. We are proud to report that the water provided by the District meets or exceeds established State and Federal standards for appearance, safety and water-quality standards. Each spring the District sends a “Water Quality Report” to every customer. The report details the District’s water quality analysis for the previous year. It also includes additional health information, information for sensitive people, and a detailed list and quantity of all detected compounds.

What do I do if I own a RENTAL PROPERTY in the District?

If you are the owner of a rental, you must have an “Owner Account”. You will need to call the office and we will set one up for you. You will start receiving a duplicate copy of the renter’s bill, which allows you to know if your renter is making their payments.

When you know the date your renter is moving in or out, notify us immediately. We will schedule a meter read to close their account.  This can be done online under the Customer tab and "Start/Stop Service".  You will fill out the "Close an Account" form.

The District's fee is $25.00 to close an account. This fee is to cover field and office expenses involved to close an account.

Please note: We allow 30 days for the renter to pay the final bill before we transfer the balance onto an Owner Account if the balance remains unpaid.

You may call us to verify that the renter paid their final bill before you give back their deposit.  You may also request a final bill prior to giving back their deposit.

Please be advised, unlike any other utilities, Washington State Law requires that the “water service stay with the property” (ref. RCW 57.08.081). This means, if a renter vacates your rental property with an unpaid balance, after 30 days the Owner is ultimately responsible for the water bill.

What should I do if I leave the area for the winter, go on vacation or a temporary job assignment?

If you are planning to be away for an extended period of time, contact the District office to have the water shut off at the meter.

Inside your home, you should, shut off your hot water heater (at the circuit breaker) and open a hot and cold water faucet in the house and one outside faucet to drain the water system and leave faucets open.

To protect outside faucets from freezing, cover them with some type of insulation.

Make sure to let us know if you will be gone for over four (4) months so we can note your account and in some cases, we can put your account under a “non-use” rate. In that situation, we would need to have specific departure and return dates.

When you return, shut off all faucets and turn on the water at the meter. Open faucets one at a time to remove any air in the line. Turn the water back on in the house and check for any leaks by watching the water meter for movement.

What should I do if I plan to move?

If you are a homeowner or a tenant the procedure is the same. Simply go to the "Customer" tab, "Start/Stop Service" and fill out the appropriate form. We will need to know the closing date; new owner/tenant name (if known); and forwarding address information. If you are selling your home and going through escrow, the Escrow Company will usually fax a final bill request to our office. We encourage both the previous and new owner/tenant to call us.

When and where are the Board meetings?

The regularly-scheduled Board meetings are held on the first and third Tuesday of each month, commencing at 4:30 p.m. The public is encouraged to attend. If you have item(s) and/or concerns you would like included on the agenda, please contact the office during normal business hours. Your request must be received at least 48 hours prior to meeting dates.

Where does our drinking water come from?

The District purchases approximately 70% of its water from Seattle Public Utilities (SPU). SPU draws its water from the Cedar and Tolt rivers. Additionally, 30% of our water is produced from our own well. The water you normally consume from KCWD 90 comes from the Cedar River and our well.

What if I have a complaint?

Any complaints or concerns should be directed to our District staff who will work with you in resolving your complaint and/or concerns. Unresolved complaints can be taken to the Board of Commissioners.