Preparing Your Septic System for Hawaii's Wet Season

Hawaii's wet season, which typically runs from November through March, brings heavy, sustained rainfall to many parts of the islands. While the rain is essential for the ecosystem, it poses a significant threat to residential septic systems. When the ground becomes saturated, your septic drainfield loses its ability to absorb and filter wastewater, leading to dangerous sewage backups.

At Advanced Compliance Solutions, Inc. (ACSI), we see a sharp increase in emergency calls during the winter months. Fortunately, a little preparation goes a long way. Here is a factual guide on how to prepare your septic system for Hawaii's wet season before the heavy rains arrive.

1. Divert Surface Water Away from the Drainfield

Your septic drainfield is designed to handle a specific volume of wastewater from your home. It is not designed to absorb the runoff from your roof or driveway. The most effective way to protect your system during the wet season is to ensure that surface water is directed away from the drainfield area.

Inspect your home's gutters and downspouts. If they discharge water near the septic tank or drainfield, install downspout extensions to redirect the flow downhill and away from the system. Additionally, ensure that your yard's natural grading does not funnel rainwater into a puddle directly over the drainfield.

2. Schedule Preventative Pumping

If your septic tank is nearing its recommended pumping interval (typically every 3 to 5 years), schedule a professional pump-out before the wet season begins. A tank that is already full of solid sludge and floating scum has less capacity to handle sudden surges in wastewater.

Pumping the tank in the dry season is also safer for your property. Pumping a tank when the surrounding soil is completely flooded can cause the empty tank to become buoyant and physically float out of the ground, destroying the plumbing connections.

3. Stagger Heavy Water Usage

During periods of heavy, continuous rain, your drainfield is already working overtime to absorb natural groundwater. You can help prevent a backup by reducing the amount of water you send into the system from inside the house.

Instead of doing five loads of laundry on a single rainy Saturday, stagger your loads throughout the week. Avoid taking excessively long showers, and wait until the dishwasher is completely full before running it. By spacing out your water usage, you give the saturated drainfield time to recover between doses of effluent.

4. Never Drive or Park Over the System

While you should never park vehicles over your septic system, it is especially critical during the wet season. Saturated soil is soft and easily compacted. The weight of a car or heavy equipment can crush the perforated PVC pipes in the drainfield or compact the soil so tightly that it can no longer absorb water.

If you have landscaping crews or construction contractors visiting your property, clearly mark the boundaries of your septic tank and drainfield with flags or stakes so they know to avoid the area.

When to Call a Professional

If you experience a severe storm and notice your toilets flushing slowly, gurgling sounds in your pipes, or foul odors in the yard, stop using water immediately. These are signs that the drainfield is flooded and the system is backing up.

Do not attempt to open the septic tank yourself during a flood, as raw sewage contains dangerous pathogens. Contact ACSI at 808-645-4672 or visit acsihawaii.com. Our engineers can provide emergency triage, assess the damage, and determine if the system needs professional remediation or replacement.