Onsite wastewater systems protect public health only when the site, soil, system type, installation, inspection, and maintenance all match current local requirements. A planning screen can organize septic tank, drainfield, pump, mound, ATU, setback, and cost questions, but it cannot replace state or county health-department rules, a site evaluation, perc or soil morphology work, product approvals, a permit, or qualified designer and sanitarian review.
This guide frames the ToolGrit septic rows as source-boundary prompts. Use them to identify what must be verified before design, repair, installation, real-estate decisions, bids, or permit submittals.
How Percolation Tests Work
Perc and soil prompts should come from the local accepted site-evaluation process. Some jurisdictions use percolation testing, some rely heavily on soil morphology, and many require a certified evaluator, soil scientist, or sanitarian. The app selector cannot identify restrictive layers, groundwater flow, seasonal high-water indicators, fill, slope, floodplain, setbacks, or replacement-area limitations.
Use local perc or soil data only after confirming test depth, test location, number of holes, water-table and bedrock evidence, property boundaries, wells, surface water, utilities, and the health-department rule set. A passing local prompt does not prove the site is buildable.
Septic Tank Sizing by Bedrooms and Flow
Tank rows in the app are local planning prompts. Actual tank volume, compartment count, filters, risers, materials, baffles, product approvals, and inspection access depend on the adopted local rule and permit conditions. Bedroom count, occupancy, future expansion, accessory dwelling units, garbage disposal rules, water softener discharge, fixture use, and commercial or high-strength wastewater can change the design basis.
Use tank output to frame questions, not to order a tank. Verify product data, manufacturer instructions, local approvals, installation depth, traffic loading, buoyancy, service access, and pumping/maintenance requirements.
Drain Field Sizing and Absorption Rates
Drainfield rows combine daily-flow and absorption prompts to produce local trench and footprint numbers. They do not determine the long-term acceptance rate, trench bottom elevation, distribution method, pressure network, dosing schedule, chamber equivalency, fill material, construction method, reserve area, or inspection result.
Local rules may require specific loading rates, trench widths, spacing, depth, cover, reserve area, setbacks, slope limits, fill restrictions, and installation procedures. Field layout should be reconciled with a current survey, soil evaluation, site plan, permit conditions, and qualified design review.
System Types: Conventional, Pressure, Mound, and ATU
The app offers conventional, pressure, mound, and ATU prompts because EPA describes multiple decentralized system types, but local approval controls which type can be used. Pressure and mound systems need hydraulic design, pump controls, elevations, sand/fill specifications, distribution details, inspection, and operation requirements.
ATU prompts are not product certification. Verify the exact unit listing, NSF/ANSI or local certification status, manufacturer instructions, power and alarm requirements, effluent limits, disinfection if required, maintenance contract, monitoring, and local acceptance before relying on an ATU reduction.
Maintenance, Pumping Schedules, and Longevity
Maintenance schedules depend on tank size, household use, solids accumulation, filter condition, pump or ATU equipment, local rules, and service records. The app does not set a pumping interval, diagnose a failing system, approve repairs, or determine whether drinking water is protected.
Keep pump-out records, inspection findings, repair notes, maintenance contracts, alarms, and as-built drawings with the property file. When wells or nearby surface waters are present, follow local health-department and water-testing guidance.
Septic Tank & Drain Field Sizing Calculator
Size septic systems including tank capacity, drain field absorption area, and pump chamber based on bedroom count, daily flow, and soil percolation rate. Covers conventional, pressure, mound, and ATU systems with setback checks.