Water Operator

At Si Enviro, we are committed to the satisfaction of you, the customer.  We strive to meet all of your needs when it comes to the most precious resource on the planet: WATER.


View or Pay Water Bill

If you would like to review your invoice, check your balance or even pay your bill online (where applicable), please visit http://sienv.firstbilling.com.

  • Visa/MasterCard/Discover/AMEX (3% Convenience Fee*) – Will post next business day
  • Electronic Check ($1.00 transaction fee*) – Will post within 2-3 business days
  • Sign up for Paperless Billing via the link above and have the option of paying your bill directly from your email by clicking PAY NOW using Visa/MasterCard/Discover/AMEX (3% Convenience Fee*) – Will post next business day

Keep in mind that delinquent payments made online could take 24 hours to process and do not guarantee immediate reinstatement of service once disconnected.


You can now also pay your water bill by phone!  Simply call us at (888) 949-9036 for CORNERSTONES MUD

The First Billing Services office is open Monday – Friday from 8:00AM– 4:30PM CT.

  • You will need your Customer Account Number and payment information.
  • Visa/MasterCard/Discover/AMEX (3% Convenience Fee*) – Will post next business day
  • Electronic Check ($1.00 transaction fee*) – Will post within 2-3 business days

You can also contact the 24 hour automated phone bill payment system. The phone number for your district is located on your bill.

Text and Pay Using Your Mobile Device

  • Visa/MasterCard/Discover/American Express (3% Convenience Fee*) – Will post next business day
  • Electronic Check ($1.00 transaction fee*) – Will post next business day

Monthly Auto-draft (drafted on due date)

  • Credit Card (3% Convenience Fee*)
  • Bank Draft ($1.00 Per Transaction*)
  • Activation completion indicated by first invoice that states “DO NOT PAY”

All Walmart Stores Internationally

  • Convenience fee varies – see store for details*

Western Union Quickpay Locations (various HEB, Kroger and Fiesta stores)

  • Convenience fee varies – see store for details* – Will post within 2-3 business days

Bill-Pay Through Your Banking Institution**

  • Please be sure to include your account number when setting up bill-pay through your banking institution (up to 10 days for processing from the date that the bank issues the payment)


  • Checks sent via the USPS
  • This includes online bill-pay through your banking institution
  • Remittance address:
  • PO Box 4824
    Houston, TX 77210-4824

Drop Box

6420 Reading Road
Rosenberg TX 77471


* These charges are third party transaction charges that are not associated or collected by Si Environmental, LLC. or your water utility district.

** Online Bill-pay through your banking institution generally involves your bank utilizing a third party to create a check that is sent to the address that you specify. Si Environmental, LLC. has no control over the check creation and mailing process for this service. All payments are processed within 24 hours of receipt by Si Environmental, LLC.

Questions About Your Bill

If you have a question about your water bill or service problems, please call Si Environmental at (832) 490-1600, Monday through Friday, 8 a.m. to 4 p.m., or email CustomerCare@SIEnv.com.  For service problems after hours or on weekends, call (832) 490-1601.

Report an Emergency

Please call us immediately at (832) 490-1601 (Local) or 1 (877) 382-7416 (Toll Free) if you have an emergency to report, such as:

  • Water Leak
  • Loss of Pressure
  • Service Interruption
  • Water Main Break in your Area
  • Sanitary Sewer Stoppage
  • Public Health Hazard

Water Rates

The following rates are effective September 17, 2018.  The cost of your service is based on consumption, with a minimum monthly charge.  This covers the cost of water transmission, treatment, and distribution.  Charges are also based on meter size and covers the cost of meter reading and billing, customer service, meter replacement and repair, system capacity, water conservation, and administration.  Billed amounts are based on meter readings for the previous month.

Usage (gal.)
Rate/1,000 gal.
Over Minimum
Levels (gal.)
10,001 to 20,000
20,001 to 30,000
over 30,000
North Lake Village
Cornerstone Place
over 30,000
over 30,000
All others
over 30,000


In addition to the foregoing rates, the Consumer shall pay a North Fort Bend Water Authority Fee per thousand gallons, equal to the pumpage fees per thousand gallons of water that the District is required to pay, if any, to the North Fort Bend Water Authority with respect to water that is delivered to the Consumer. Note: The information provided above is a summary of the District’s services and rates (based on residential 3/4″ meter), which are qualified in their entirety in the District’s complete statement of its rates, rules and policies, and by local, state and federal regulations, and are subject to change without notice.

Tax Rates

5-Year Tax Rate History
2011 – $0.17   + 0.19
2012 – $0.165 + 0.195
2013 – $0.165 + 0.195
2014 – $0.15   + 0.19
2015 – $0.13   + 0.20
2016 – $0.125   + 0.175

Regional Water Authority

Cornerstones MUD participates in a regional water authority (RWA) whose mission is to reduce the use of well/ground water and increase the use of surface water. Reducing dependence on well water leads to a reduction in ground subsidence as required by Texas state law. Districts are required to reduce ground water usage by 30% by December 2013, the current plan is for Cornerstones MUD to convert to surface water no later than 2025. The North Fort Bend Water Authority (NFBWA) was created in 2005 to allow well owners like Cornerstones MUD to band together to mutually accomplish this mission. The NFBWA borrowed $300 million to finance water pipeline construction that extended from the City of Houston to northern Ft. Bend county. This water pipeline currently provides surface water to approximately 30 MUD’s inside the NFBWA footprint. By over-conversion to surface water in those Districts, the remaining Districts in the NFBWA footprint can continue to use ground water until the next required reduction no later than 2024.

The RWA fee included on your monthly invoice provides for re-payment of the borrowed funds and ongoing operations of the Authority. The NFBWA increased that fee from $2.70 per 1,000 gallons used to $3.05 per 1,000 gallons used effective January 1, 2017. Cornerstones MUD’s rate order required that this fee be passed through to you the consumer at cost. This fee is expected in increase annually as NFBWA is planning to borrow more funds to build additional water infrastructure.

SI Environmental handles all billing and payments for Cornerstones MUD.

Summary of Water Conservation, Drought & Emergency Contingency Plan

The District’s Fourth Amended Drought Contingency Plan was adopted on November 19, 2012, for times of severe shortage of rainfall and decreased water supply, and to ensure that adequate supplies of water are maintained in the District.  During such times, the District will distribute information to its residents and other users of water regarding water conservation.

In general, drought conditions are reached when the water supply reaches 80% of the District’s production capacity for three consecutive days.  During such times, the following measures are taken:

  1. The District will inform water users of the drought conditions, and any restrictions on water use by notices and press releases.
  2. During mild drought conditions (75% capacity), the District will recommend that users voluntarily reduce water use.  Outdoor water use (lawn watering, car washing, etc.) will be limited as follows: even-numbered addresses may use water outdoors only on Wednesdays and Sundays and odd-numbered addresses may use water outdoors only on Tuesdays and Saturdays.  Outdoor water use shall be prohibited between the hours of 7:00 a.m. and 10:00 a.m., and between the hours of 6:00 p.m. and 10:00 p.m.
  3. During moderate drought conditions (85% capacity), in addition to the above requirements, outdoor water use may be conducted with a hand-held hose only.  The District will also recommend that non-essential water usage such as the filling of swimming pools and street washing be curtailed.
  4. During severe drought conditions (90% capacity), outdoor water use will be prohibited, a surcharge will be applied on water use in excess of 10,000 gallons per month, and in emergency situations the District may prohibit water use not essential to health and safety related uses, and impose penalties for violation of emergency response measures.  These penalties may include written notification for the first violation, and monetary penalties and discontinuation of service for subsequent violations.  Variances may also be granted for emergency conditions affecting health, sanitation and fire protection.

The above summary is provided for information purposes only.  For a complete understanding, please click here for the complete Drought Contingency Plan.