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Mobile Water Treatment Methods

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MWTS Approval Process

A water provider who uses a MWTS to treat groundwater sources for drinking water or human consumption purposes is subject to the following requirements: 

  • Each MWTS will be approved and operated as a separate PWS. The MWTS shall be considered as serving one single Point of Use Entry Point (POU EP). This is where the bacteriological, chemical, and disinfectant compliance monitoring will occur.
  • An exception to 30 TAC 290.42(g) must be secured for each MWTS, and the MWTS must have engineering plans and specifications approved by TCEQ in accordance with 30 TAC 290.39.
  • All planning material and business plans shall be submitted in a manner consistent with a new PWS. 30 TAC 290.39(e) and (f)
  • All components of the MWTS and any associated treatment chemicals and media must be certified by the American National Standards Institute/National Sanitation Foundation International (ANSI/NSF) for potable water use under 30 TAC44(a)(1) and 30 TAC 290.42(j).
  • All proposed MWTS operations must conduct bacteriological sampling before utilizing an unapproved groundwater source for potable use. Based on the regulations required for new public water sources, once three consecutive daily samples are collected and the certified laboratory results for all three samples are shown to be “absent” for total coliform, the MWTS may proceed with treating the source for potable use.  In lieu of this sampling requirement, the MWTS may utilize a LT2 challenge tested / TCEQ approved cartridge filter to treat 100% of the flow through the treatment unit, in addition to the RO and other treatment provided.
  • Baseline “worst case” water quality parameters (WQPs) which the MWTS is able to treat effectively shall be established by a professional engineer licensed in the State of Texas and substantiated by the submission of reverse osmosis (RO) modeling as allowed by 30 TAC 290.39(e)(6)(C) and verification data from a laboratory accredited by TCEQ (National Environmental Laboratory Accreditation Program (NELAP)) to perform these tests. Actual MWTS results including pretreatment water and final product water will be required.
  • Baseline parameters will be tested on the site and subsequently verified by NELAP testing.
  • The design of the MWTS cannot be approved based solely on RO modeling; the PWS can conduct a pilot study which demonstrates the effectiveness of treatment for particular water quality parameters under an exception request to provide Innovative/Alternate Treatment as outlined in 30 TAC 290.42(g). Alternatively, the PWS may submit modeling and verification data from a laboratory accredited by TCEQ (National Environmental Laboratory Accreditation Program (NELAP)) to perform these tests of actual MWTS results including pretreatment water and final product water.  The applicable portions of the TCEQ “Membrane Construction Checklist (Step 1)” should be used as a guide to the data submittal requirements.
  • The operating parameters (such as flow rates, cleaning intervals, pretreatment chemical dosages, and post-treatment, and chemical dosages) must be appropriate for the feed water quality to the MWTS. The operation of each MWTS shall be limited by a "worst case" feed water quality.  For membrane technologies, the licensed engineer must have sufficient data for the constituents that affect the efficiency of the MWTS, cleaning intervals, and/or cause scaling or fouling. At a minimum, the feed water quality analysis must include the ion concentrations for all constituents listed in the table below and those required by the manufacturer's model (if RO or nanofiltration is used). In all cases, the feed water to the MWTS shall be limited to the water quality used for the demonstration (modeling, pilot testing, and/or water quality limitations of the equipment manufacturer) of the unit and approved baseline values. Therefore, prior to submitting data for MWTS approval, consideration must be given to water quality variability.  This variability may be due to site location, blending ratios with other sources, and/or seasonal changes.
  • Each groundwater source to be treated by a MWTS must be analyzed for the following analytes as well as those required by the manufacturer's RO model, using EPA approved laboratory methods. The analytical results must come from a TCEQ accredited laboratory with a current National Environmental Laboratory Accreditation Program (NELAP) certification. 
  • Primary Contaminants and Maximum Contaminant Levels (MCLs)
    • Nitrate: MCL - 10 mg/L (as N)
    • Nitrite: MCL - 1 mg/L (as N) 
  • Secondary Constituents and Secondary Constituent Levels (SCLs)
    • Aluminum: SCL - 0.2 mg/L
    • Chloride: SCL - 300 mg/L
    • Copper: SCL - 1.0 mg/L
    • Fluoride: SCL - 2.0 mg/L
    • Iron: SCL - 0.32 mg/L
    • Manganese: SCL - 0.05 mg/L
    • pH: SCL - ≥ 7.0
    • Sulfate: SCL - 300 mg/L
    • TDS: SCL - 1000 mg/L
    • Zinc: SCL - 5.0mg/L 
  • Lead and Action Level
    • Lead: Action Level – 0.015 mg/L 
  • Corrosion Control Parameters
    • Alkalinity (as CaCO3)
    • Calcium (as CaCO3)
    • Sodium 
  • Before a MWTS can be used at a groundwater source, a raw water sample must be collected and The results must be compared to the baseline treatable WQPs.  If the water quality of the source is equal to or better than the baseline treatable WQPs, the owner of the MWTS may proceed with hook-up and treatment.  If the water quality of the source is worse than the baseline treatable WQPs, the owner must contact the Technical Review and Oversight Team in TCEQ’s Water Supply Division at (512) 239-4691 and water may not be produced from that source.
  • Any of the water sources stated below are not considered groundwater sources and are prohibited: water that has been pumped into open ponds (even if the ponds are lined and bermed); water that is stored in tanks that do not meet all the requirements in 30 TAC §290.43; water provided by a water hauler without a PWS ID; and water provided by a water hauler that is not procured from an active public water system.
  • The baseline treatable WQPs established for a MWTS may be changed based on the submission of new NELAP Laboratory data or pilot study results and approval of those new results by the TCEQ.
  • The raw water source cannot be exposed to the atmosphere to ensure no biological contamination occurs. All storage and treatment units of the MWTS must be fully enclosed and all vents properly screened. 
  • The MWTS must meet the minimum free chlorine disinfection requirements of at least 4-log treatment of viruses before water is distributed to any customer and shall maintain acceptable disinfectant residuals at the POU EP.
  • All lines, tanks, and applicable components of the MWTS must be disinfected in accordance with American Water Works Association requirements before being connected to a new groundwater source.
  • The proposed MWTS may not transfer water from one site for use as potable water at a different site. The treatment rig must be completely drained on-site before the rig may travel to the next treatment site.
  • A MWTS that stays on a site for 60 or more days per calendar year in accordance with the definition of a Public Water System in 30 TAC 290.38(71) is no longer considered a MWTS. After 60 days of operation at a single location, the raw water source and any associated potable water distribution piping will meet the definition of public water system facilities and the site will be subject to all applicable regulations regarding sources and distribution, as either a transient non-community or non-transient non-community PWS (if serving at least 25 of the same people for six months out of the year).
  • The proposed MWTS must provide adequate post-treatment and remineralization to ensure that the water provided for human consumption at the point of use entry point is stable with a pH equal to or greater than seven (pH ≥7).

Cross-Connection Control and Backflow Prevention

The MWTS owner or site operator shall ensure that any cross-connections on the piping conveying the raw water source to the MWTS are adequately protected by requiring a reduced-pressure principle backflow prevention assembly (RPBA) or air gap.  Examples of potential sources of contamination may include, but are not limited to:

  • Groundwater sources exposed to atmospheric contamination;
  • Surface water sources; or
  • Housing, commercial, production, or industrial operations.

The MWTS owner or site operator shall ensure that the MWTS is protected from actual or potential contamination hazards by requiring an RPBA or air gap after the last treatment process and prior to the Point of Use Entry Point. 

Testing requirements for RPBAs installed to provide protection against health hazards will apply per 30 TAC 290.44(h)(4).

Design, Operation, Maintenance, Compliance Monitoring and Reporting Requirements

When a MWTS is approved, the owner will receive an approval letter with detailed, site-specific design, operation, maintenance, compliance monitoring and reporting requirements.  The compliance monitoring and reporting requirements will be in accordance with those for a transient noncommunity public water system.  The required NELAP laboratory samples must be submitted for microbiological and chemical analyses using EPA-approved drinking water methods to one of the commission's accredited laboratories. Please note that two accredited drinking water laboratories, the Texas Department of State Health Services (DSHS) and the Lower Colorado River Authority (LCRA), report sample results directly to the TCEQ using electronic data transfer.  If the owners or site operators of a MWTS choose to use an accredited laboratory other than DSHS or LCRA, then the results of compliance sampling must be submitted electronically by that laboratory to the TCEQ.  For questions regarding the electronic submission of compliance samples to the TCEQ, please contact a member of the TCEQ Drinking Water Quality Team at (512) 239-4691.  Failure to comply with the conditional approval may result in violations, enforcement action, and/or revocation of the approval to use the MWTS.  

Owners and operators must maintain documentation demonstrating compliance with the conditions of the approval letter and all applicable PWS requirements. Some documents must be submitted to TCEQ on a regular basis for review and other must be kept on site and provided to the executive director or representative upon request. MWTSs are subject to TCEQ investigations to evaluate compliance with PWS requirements.

MWTSs shall provide startup and shutdown information to the appropriate TCEQ Regional Office via mail, email, or facsimile, with a copy to the PWS Liaison in the Program Support Section of the Office of Compliance and Enforcement.

A relocation form has been developed for reporting location change and startup of activities (see attached).  This form has a submit function to submit by email to the PWS Liaison.  The appropriate TCEQ Regional Office may be sent the same email.  There is a link for regional contact information on the form.  You may also contact the PWS Liaison with questions at, and the Water Supply Division Inventory Program, current at

The operators of the proposed MWTS must record and maintain daily logs that state the geographical location of the unit for every day it is in operation. These records must be kept on file for ten years and made available to TCEQ personnel upon request.