Swimming Pool Efficiency for Cities


  • Pools use considerable amounts of energy to meet health and safety standards and ensure acceptable water quality. Variable speed pull pumps are an underutilized opportunity to save energy and cost in municipal pool operation.
  • The City of San Antonio, Texas was able to save approximately $63,000 per year by installing variable speed drives in 22 municipal pools. Being the first of its kind, it involved a three year process of stakeholder engagement, research, and confirmation of safety standards.
  • Few resources exist for municipal pool energy efficiency projects. Further research and pilots can support more extensive retrofit of pool equipment.

Municipal Swimming Pool Efficiency

Municipal swimming pools are an often overlooked opportunity for local governments to achieve energy, water, and cost savings. Health and safety standards mandate pool water “turns over” three to four times a day, meaning the entire volume of water is filtered every six to eight hours. Furthermore, it is typical for pool pumps to be oversized to accommodate increased filtration during high-use periods. Cities can reduce electricity use without compromising pool water quality at their swim facilities by optimizing filtration schedules and retrofitting with variable speed pumps.

Pool retrofit projects remain infrequent due to health and safety regulatory concerns and lack of precedent projects. In 2014, the City of San Antonio performed the first municipal swimming pool retrofit project in the country – proving that it is possible to both comply with health and safety standards and reduce energy consumption through swimming pool retrofits.

As more schools, cities, and municipalities implement swimming pool retrofit projects, further best practices will emerge.

Case Study: Retrofitting Municipal Pools in San Antonio

Energy conservation in commercial pools was a novel concept when San Antonio started its swimming pool retrofit project. The City led a three-year process of stakeholder engagement, training, and equipment testing that resulted in the installation of variable frequency drives (VFDs) on its pool pumps – the first ever retrofit of its kind.

By the end of the project, San Antonio had retrofitted 22 of its 26 pools with VFDs. The city utilized utility rebates from CPS Energy to reduce the project cost which resulted in an overall project payback period of less than one year.

The city saved approximately $63,000 per year by performing its swimming pool retrofit, and achieved a 24% energy savings in its pool facilities. San Antonio’s pool project received national attention including media coverage.

Read the full case study for step-by-step detail of how San Antonio initiated and completed its project.

Best Practices

Several best practices emerged from San Antonio’s pool retrofit project:

  • Reach out to the Texas Department of State Health Services (TDSHS) and your local health departments at the beginning of the project planning to help define specific standards for pool water quality.
  • Baseline pool energy consumption before retrofit and track energy consumption to verify energy savings and ensure proper operation over time.
  • Engage your operations and maintenance staff early in the process to gain buy-in and include them in key decisions.
  • Be sure to involve pool operators in the entire project and set them up to succeed by providing as much training and materials as necessary.

Texas Pool Standards

Understanding regulatory standards and best practices around health and safety is the first step in any pool energy efficiency project. The state of Texas outlines its mandatory statewide standards for public pools in the Texas Administrative Code, Title 25, Part I, Chapter 265, Subchapter L.

Pools built before October 1st 1999 must achieve a water turnover rate of 8 hours, and pools built after October 1st 1999 must achieve a water turnover rate of 6 hours. Further technical details on circulation system requirements in Texas can be found in RULE §265.187 here.

When pool equipment is replaced or installed, it must meet the ANSI and NSFI Standard 50.

The Texas Department of State Health Services (TDSHS) provides a downloadable and printable version of these rules online here.

TDSHS also provides guidance documents, forms, and contact information here for further assistance.

Existing and Further Research

Further technical research, data, and case studies on variable speed pool pump retrofits in commercial pools is needed to support municipal and school projects. Quality data verifying safety and savings helps city staff make the case to city leadership for reducing energy waste through installing variable frequency drives.

The primary research study to date is the US Department of Energy National Renewable Energy Laboratory’s (NREL) report “Measure Guideline: Replacing Single-Speed Pool Pumps with Variable Speed Pumps for Energy Savings. Although the report focuses on residential applications, the research and concepts in the report were highly influential to San Antonio’s project.

Documents and fact sheets from US Department of Energy’s defunct Reduce Swimming Pool Energy Costs (RSPEC) program are still available online to help organizations reduce their swimming pool energy costs.