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Long Term 2 Enhanced Surface Water Treatment Rule

Information regarding the Long Term 2 Enhanced Surface Water Treatment Rule (LT2) source water monitoring for public water systems. The purpose of the LT2 rule is to reduce illness linked with the contaminant Cryptosporidium and other disease-causing microorganisms in drinking water. The rule supplements existing regulations by targeting additional Cryptosporidium treatment requirements to water sources that show higher Cryptosporidium levels.

LT2 Schedule

LT2 requires systems that use surface water or groundwater under the direct influence of surface water to sample their source water during two rounds of sampling. The first round of source water sampling has been mostly completed by most public water systems, and the second round is just beginning. LT2 requires water systems to start Round 2 for source water monitoring per the following table:

Raw Source Water Monitoring Schedule

Systems that are not part of a combined distribution system(1) and serve . . . must begin the first round of source water monitoring no later than the month beginning . . . and must begin the second round of source water monitoring no later than the month beginning. . .
At least 100,000 people are Schedule 1 and October 1, 2006 April 1, 2015
From 50,000 to 99,999 people are Schedule 2 and April 1, 2007 October 1, 2015
From 10,000 to 49,999 people are Schedule 3 and April 1, 2008 October 1, 2016
Fewer than 10,000 people are Schedule 4 and which monitor for E. coli October 1, 2008 October 1, 2017
Fewer than 10,000 people are Schedule 4 and which monitor for Cryptosporidium April 1, 2010 April 1, 2019

(1)Systems that provide treated surface water to another system and are part of a combined distribution system must begin monitoring at the same time as the system in the combined distribution system that has the earliest compliance date.

For further information on Round 1 and Round 2 of the LT2 Rule please contact:

You may also see the EPA information for the LT2 RuleExit the TCEQExit the TCEQ.

Sampling Plan Deadlines

These deadlines relate to rules for monitoring and controlling Cryptosporidium:

Public Water System


Sampling Plan

Submittal Date

Date to

Begin Sampling

Tests to Perform

on Samples

Schedule 1 January 1, 2015 April 1, 2015

Cryptosporidium, E. coli,


Schedule 2 July 31, 2015 October 31, 2015

Cryptosporidium, E. coli,


Schedule 3 July 1, 2016 October 1, 2016

Cryptosporidium, E. coli,


Schedule 4

(E. coli)

July 1, 2017 October 1, 2017 E. coli

Schedule 4


January 1, 2019 April 1, 2019 Cryptosporidium

Sampling Plan Submittal Date

TCEQ must be informed in writing how you plan to meet sampling requirements. There are two options based on your Schedule:

  1. If you are a Schedule 1-3 system, submit to the TCEQ a sampling plan that includes a sampling schedule and a description of the sampling location by the date in the Sampling Plan Deadlines table above, OR
  2. If you are a Schedule 4 system, send the TCEQ a letter stating whether you plan to sample for E. coli or Cryptosporidium. Based on the test to be performed, submit to the TCEQ a sampling plan that includes a sampling schedule and a description of the sampling location by the date in the Sampling Plan Deadlines table above. Please note that there are different dates for Schedule 4 E. coli and Cryptosporidium.

 Sampling plan documents that must be submitted to the TCEQ:

  • Sampling Location Worksheet. One per treatment plant.
  • Sampling Schedule.
  • Diagram for Sampling Location. One per sampling location.

Materials to Help You Meet These Deadlines

Prior to the sampling plan submittal date, the TCEQ will mail each system a sampling plan materials package to aid in the submittal of the required information. If you did not receive your package or would like these materials in electronic format, please use these files (help with PDF files):

Sampling Requirements

  • For Schedule 1-3 systems, sample for Cryptosporidium, E. coli, and Turbidity monthly for 24 months. The Cryptosporidium testing should include 2 matrix spikes for a total of 26 samples.
  • For Schedule 4 systems:
    • For E. coli, sample every 2 weeks for a year (a total of 26 sampling events).
    • For Cryptosporidium, sample monthly for 24 months, to include two matrix spikes or 26 total samples.
  • In any sampling event that includes E. coli, E. coli colonies must be enumerated. In other words, colonies must be counted; “presence/absence” results are not sufficient.
  • All E. coli and Turbidity samples must be analyzed by a TCEQ-accredited laboratory.

Below is a link that you may find helpful:

Submittal of Results

Systems should begin sampling per the schedule detailed in their sampling plan. Systems should submit a copy of the sample results from the lab to the TCEQ.

  • Submittal Deadline: The 10th day of the month following the period for which you are reporting. For example, for the month of May, submit the sample results by June 10. Please submit your available LT2 laboratory report(s) for the month as per the TCEQ LT2 Report Submittal.
  • Sampling Window: Remember you must take your sample within 2 days of the declared sample date on your sample schedule

Here is a quick reference guide for submittal of results to the TCEQ:

  • TCEQ LT2 Report Submittal Adobe Acrobat PDF Document

If you have not submitted your sampling plan, please see the Sampling Plan Deadlines table above.

Rules for These Deadlines

The federal LT2ESWT RuleExit the TCEQ Federal Register January 5, 2006. The Texas version of this rule, Title 30 Texas Administrative Code Chapter 290Exit the TCEQ Texas Register January 4, 2008, and took effect January 9, 2008.

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