The District’s water system, is a shared system with Harris County Municipal Utility District No. 364 (MUD 364) and consists of three water wells, storage tanks, pumps, pressurization tanks, and miles of pipe to deliver the water to your homes. This system provides water to the residents of Coles Crossing (MUD’s 364,365), The Park at Arbordale (MUD 365), and Stillwater Village (MUD 364), as well as a few surround commercial properties.

The Sanitary Sewer system is a shared system with Harris County Municipal Utility Districts 365 (MUD 365) & 364 (MUD 364) and consists of lift stations, wastewater treatment plant, and miles of pipe to take wastewater from your home to the wastewater treatment plant. The Sanitary Sewer system only collects waste water from home and businesses, it does not collect rainfall runoff. Rainfall runoff is handled by the storm water system which drains to our retention pond and this Cypress Creek.

All the facilities have been equipped, or are in the process of being equipped, with backup power generators to ensure continuous water and sanitary sewer service to our customers.

Water & Sewage Operators: Si Environmental, LLC

6420 Reading Road, Rosenberg, Texas 77471
Phone: (832) 490-1500; Fax: (832) 490-1501
Customer Service:

Do you have an Emergency?
832-490-1601 – Local Dialing
1-877-382-7416 – Toll Free

Water Rates

The District’s water and sewer service rates escalate with higher usage in order to encourage water conservation and responsible use by the District’s residents. For a single family home, the District’s water and sewer rates are as follows:


0 – 10,000 gallons
$5.00 minimum bill

10,001 – 15,000 gallons
$1.00 per 1,000 gallons

15,001 – 25,000 gallons
$1.75 per 1,000 gallons

25,001 – 35,000 gallons
$2.50 per 1,000 gallons

35,001 to 60,000 gallons
$3.50 per 1,000 gallons

Above 60,000 gallons
$5.00 per 1,000 gallons


Flat Rate $14.00 per month

North Harris County Regional Water Authority Fee

10/1/23: $3.60 per 1,000 gallons

The District’s operator reads all the meters within the District on a monthly basis and handles the District’s billing and customer service matters. If you have any questions regarding your water and/or sewer service, please contact SI Environmental at (832) 490-1600 or All customer calls to SI Environmental are reported to the Board of Directors at its monthly meeting.  If you have an emergency repair to report, call the 24 hour hotline at (832) 490-1601.

Water Reports and Plans

Water and Sewer FAQs

What is the “RWA FEE” line item on my bill?

“RWA” is one of the acronyms used to refer to the North Harris County Regional Water Authority. The North Harris County Regional Water Authority is also often abbreviated with the acronym “NHCRWA” (the acronym you will find in the Water Authority’s own materials). When you see these different acronyms, they are both used to refer to the same water authority. The “RWA FEE” you see on your bill is a pass-through fee charged by the NHCRWA to a MUD based on the amount of groundwater pumped and/or the amount of surface water received from the NHCRWA. The fee charged to the MUDs within the boundaries of the NHCRWA is not optional. NHCRWA typically reviews its rate structure and pricing annually and publishes new rates, which can be found in various publications on the NHCRWA website, including in this Updated Pricing Policy linked here.

What is the North Harris County Regional Water Authority (NHCRWA)?

The North Harris County Regional Water Authority, sometimes referred to simply as the NHCRWA or the RWA, is the entity responsible for securing a long-term, reliable supply of wholesale drinking water in our area, designated as North Harris County. As part of this ongoing process, the NHCRWA is in the process of building additional infrastructure to bring surface water, mostly from Lake Houston, to many Municipal Utility Districts, or MUDs, in our area with the goal of converting from the use of ground water (wells) to surface water (lakes, reservoirs) in certain designated areas. More details on the North Harris County Regional Water Authority and its capital improvement projects and plans for conversion can be found on the NHCRWA website at

Why must I submit a request to the MUD before building a pool or installing a sprinkler system? What is the process for making such a request?

There are several ways the Public Water System can be contaminated from cross-connections within that system. There are various inspections required when installing equipment that uses potable water for its operation or when something has a direct connection to a potable water system such as an irrigation system, spa or swimming pool.

Due to the circumstances listed above, potable water lines must be protected from possible contamination from irrigation systems and pool fill lines. Backflow may occur in the event of either Backsiphonage or Backpressure. Backsiphonage can happen when the pressure in the distribution system drops, drawing water from the consumer’s plumbing back into the system. Pressure drops might occur in the event of a main line break, or high water demand such as fighting a fire nearby. Backpressure can cause Backflow when a potable water system is connected to another system that operates at a higher pressure…such as an irrigation system or a pool fill line.

The installation of irrigation systems and swimming pools are required by the State of Texas to be inspected upon installation and sometimes annually depending on the application to ensure that the proper backflow prevention assembly is being used to protect the Public Water Supply. Residential applications are not excluded from this because the property is directly connected to the Public Water System and Backpressure and Backsiphonage may occur.

The Inspection Criteria is as follows:

1. Resident should submit set of design drawings or plans along with a check in the amount of $175 made payable to Harris County Municipal District No. 365, depending on which District you live in, for the plan review. These documents are sent to the Municipal Utility District Engineer for approval prior to commencement of construction.

Sander Engineering Corporation
1250 West Sam Houston Parkway South, Suite 400
Houston, Texas 77042
Office: (713) 784-4830
Fax: (713) 784-4052

2. The Engineer will review the plans and upon approval will forward to the inspections department of the district operator, Si Environmental, LLC.

3. Customer and/or Contractor performing installation of the swimming pool or irrigation system shall notify Si Environmental at 832-490-1610 to schedule times for the inspection of their pool installation or irrigation system. Fees for the inspections will be debited to the customer’s water bill per the district’s current Rate Order.

4. Failure to notify Si Environmental for the inspection will result in a scheduled inspection 30 days from the date on the engineer’s approval letter. Each trip to the residence for an inspection will result in a debit to the customer’s water bill for the fees associated with the inspection per the district’s current Rate Order.

Most common reasons for failing inspection:

1. Water line used to fill pool does not have approved backflow prevention device such as a hose bibb vacuum breaker permanently installed

2. Swimming pool has a direct connection fill line without proper backflow prevention

3. Backwash line for swimming pool does not have the appropriate air gap at the sanitary sewer connection

4. Backflow prevention device on swimming pool fill line does not pass the required Backflow test

5. Backflow preventor on Irrigation system is not installed properly due to location or height

Backflow prevention devices protect us all from the possibility of containments entering our drinking water system. If you have not had yours inspected for proper operation, you may wish to call a licensed irrigator, swimming pool contractor or MUD operator, Si Environmental, to confirm that it is working properly. Safety in our drinking water system is an important responsibility that we all share.

Notice of Confidentiality and Right to Request Disclosure

Pursuant to Section 182.051, Texas Utilities Code, a customer’s personal, utility usage, and billing information is confidential and may not be disclosed by the District to third parties unless a written request for disclosure is submitted by the customer. If you wish to request disclosure of this information, click here to download and complete the form for submittal to the District.


Next In-District Meeting

June 10, 2024 at 6:00 PM

May 14, 2024 at 5:00 PM

Special Meeting Agenda (PDF)

Next Business Meeting

May 21, 2024 at 11:30 AM

Agenda (PDF)


Connect with Harris County MUD 365 on Facebook