The Truth About Mulch and Septic Systems

mulch and septic system, drainfield mulchYour septic system’s drainfield requires special care. Most homeowners know, for instance, not to plant deep-root trees and shrubs in the drainfield. But you might not know that mulching can also be a problem. Most experts say that laying mulch on a septic system drainfield is not a good idea.

Mulch and Septic Systems Are not an Ideal Combination

Next to planting deep-rooted plants, mulch is the least septic-friendly landscaping practice. As a general rule, you should avoid mulching directly over the drainfield. Mulch inhibits the treatment system’s oxygen flow that’s needed for the filtration of effluent. When there isn’t sufficient oxygen, the bacteria cannot break down solid waste. This can lead to a backup requiring a septic tank pumping.

Mulching Around the Foundation

In no way are we suggesting that you avoid mulching altogether. We actually recommend mulching around the perimeter of your home. The mulch absorbs moisture that would otherwise make its way into your foundation, leading to erosion of the concrete.

It’s when you mulch directly over the septic system’s drainfield that the problem arises. The extra moisture retention strains the system, especially after a rain spell. Mulch absorbs the rainwater, which then has to be filtered through the drainfield. This is the same reason why homeowners are advised to avoid doing loads of laundry back-to-back. The excess water taxes the system too much at one time.

Improving Drainfield Aesthetics

You can improve the drainfield’s appearance without mulch. You can plant grass and other shallow-root vegetation over the field. This is also functionally beneficial as it improves oxygen exchange and prevents the build-up of excess soil moisture.

We Service Your Septic System

We recommend an OSS inspection as part of a 2020 initiative. The same goes for grease trap cleaning for business owners. Call Lil John Sanitary Services if you have been holding off regular pumping and/or inspections. Remember, be mindful that mulching and septic systems don’t go hand-in-hand.

Residential Septic System Maintenance

Serving Bellingham, Ferndale, Lynden, Everson, Deming, Lummi Island, Nooksack, Blaine, Whatcom & Skagit Counties, Maple Falls, Bow Birch Bay, Custer, and Acme