Compared with a septic tank without an effluent filter, the effluent from a septic tank with a filter is:

Compared with a septic tank without an effluent filter, the effluent from a septic tank with a filter is:

• A. The same quality
• B. Slightly worse
• C. Slightly better but not much
• D. Different quality, because the filter retains more solids making it clearer

Answer: (D)

The main idea here is how an effluent filter changes what comes out of the tank. An effluent filter is there to trap solids so they don’t pass into the drain field. Because those solids are being retained, the water leaving the tank has fewer suspended solids and is clearer, which means its quality is different from effluent that has no filter. So the correct takeaway is that the effluent quality is different—generally clearer—due to the filter catching more solids. Without a filter, more solids would enter the drain field, increasing turbidity and the potential for clogging.

The main idea here is how an effluent filter changes what comes out of the tank. An effluent filter is there to trap solids so they don’t pass into the drain field. Because those solids are being retained, the water leaving the tank has fewer suspended solids and is clearer, which means its quality is different from effluent that has no filter. So the correct takeaway is that the effluent quality is different—generally clearer—due to the filter catching more solids. Without a filter, more solids would enter the drain field, increasing turbidity and the potential for clogging.