St. Mary’s County Health Department (SMCHD) has announced that it will begin wet season perc testing for lower terrace soil types on or about February 27, 2023, due to the rising seasonal groundwater levels. This comes after the suspension of perc testing in April 2022 due to declining groundwater levels, which had led to concerns about the environmental impact of septic systems in the area.

The SMCHD’s Environmental Health Division staff conduct soil evaluations for the construction of residential and commercial septic systems. Perc testing, short for percolation testing, is an essential component of this process, which measures the rate at which water drains through soil. This information is crucial in determining the appropriate size and placement of septic systems, as well as their potential environmental impact.

However, the testing process can only be carried out effectively during certain times of the year, when groundwater levels are high enough to yield reliable results. The wet season, typically occurring between February and April, is the optimal time for perc testing, as it allows for a more accurate assessment of soil drainage.

According to the SMCHD, perc testing for all other soil types, such as upland areas, will begin when water tables reach their normal wet season range. This means that testing may not begin for all areas immediately and could be suspended if the water table recedes. The SMCHD will resume testing if water levels rebound to necessary ranges.

Community members who require perc testing can download the application for a new construction perc test through the St. Mary’s County Department of Land Use and Growth Management (LUGM) or by calling 301-475-4200, ext. 1500. The application comes with a fee, which is necessary to cover the costs associated with the testing process.

For those interested in learning more about perc testing, the SMCHD website provides a comprehensive guide at The guide covers the basics of perc testing, including why it’s necessary, how it’s done, and the potential environmental impact of septic systems.

The SMCHD has made it clear that the safety and health of the community are of utmost importance. Ensuring that septic systems are appropriately sized and placed is crucial for protecting both the environment and public health. By providing accessible and accurate soil evaluations, the SMCHD is working to mitigate the potential harm caused by septic systems and promote sustainable development practices in St. Mary’s County.

David M. Higgins II is an award-winning journalist passionate about uncovering the truth and telling compelling stories. Born in Baltimore and raised in Southern Maryland, he has lived in several East...

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