Septic companies in Ontario, CA

What the ground in Ontario is like

The USDA soil survey rates mapped ground in Ontario for septic drain-field suitability across roughly 50 square miles. About 91% of the rated ground is classed "Very limited", meaning the soil has one or more features unfavorable for a conventional drain field, and the limits generally cannot be overcome without major soil reclamation, special design or expensive installation.

In Ontario, the leading limit is seepage in the bottom layer: water moves through the soil too quickly. That is the opposite of a slow-drainage problem. The risk is untreated effluent reaching groundwater before the soil can clean it, not backup at the surface. The survey flags that limit on about 90% of the rated ground here.

The limiting features the survey records most often here:

• Seepage, bottom layer90.0%
• Filtering capacity88.3%
• Flooding56.0%
• Slow water movement10.0%

This is survey data for mapped areas, not a substitute for a site evaluation on your own lot. Conditions on a single parcel can differ from the map.

USDA NRCS SSURGO, ENG Septic Tank Absorption Fields · 91.2% Very limited · Seepage, bottom layer · 15 map units · 49.98 sq mi · read 2026-08-30