What a septic design for a Story City property has to specify, and where the numbers come from. In Story County, Iowa, which covers Story City, we have measured 6,279 parcels on septic and 22,781 on sewer. That is a county measurement. We do not hold a septic count for Story City on its own and this page does not estimate one.
| Specification | What drives it |
|---|---|
| Design flow | Bedroom count is the near-universal proxy, because it bounds occupancy in a way that current residents do not. States publish gallons per day per bedroom; the state figure governs. |
| Tank working capacity | Design flow plus the retention time the code requires, so solids settle rather than carry over into the field. Codes set a floor that rises with bedroom count. |
| Treatment level | A conventional tank delivers primary treatment. Shallow soil, a high water table, a small lot or a sensitive receiving water can force a higher level, which usually means an aerobic treatment unit or a sand filter ahead of dispersal. |
| Dispersal type | Gravity trench, chamber, pressure distribution, mound or drip. The soil profile and the available fall pick this, not preference. |
| Dispersal area | Design flow divided by the soil loading rate the evaluation established, adjusted by the code for the dispersal type chosen. |
The reserve area is the sixth item and the one most often skipped. Codes generally require space to be set aside for a full replacement field, and a design that uses the whole lot for the first field is a design that has quietly spent the property’s future.
Our collection for Story County, Iowa is small, at 311 septic records. Treat it as a starting point for a Story City property rather than a search that settles the question. The county is genuinely mixed: 6,279 of 29,060 classified parcels are on septic and the rest are sewered. Which side of that line a Story City address falls on is worth establishing before anything else. The county publishes a records portal that we were able to search without creating an account, which makes checking a specific parcel something you can do yourself in a few minutes.
Everything above turns on one measured value: how fast the receiving soil will accept effluent. A tighter soil needs more dispersal area for the same house, and past a certain point it stops being a sizing problem and becomes a system-type problem, forcing pressure distribution or a mound. This is why a designer cannot quote a real system from a lot size and a bedroom count, and why any figure offered before the soil work is a placeholder.
| County | Records we hold | Parcels on septic | Records machine-readable |
|---|---|---|---|
| Story County | 311 | 6,279 | 100% |
For a repair, replacement or addition the filed as-built is the starting point: existing tank capacity, the field footprint to work around, and the flow the system was permitted for. A system permitted for three bedrooms does not become a four-bedroom system because a wall moved.
Parcel Perfect produces a code-shaped septic design and an as-built style drawing for a parcel from the records and site data we hold for it. It is meant to give a designer, a builder or an owner a defensible starting document and a picture of what the system probably needs to be, not to replace the site evaluation or the licensed design that the county will actually permit. The soil evaluation still has to happen.
Design flow, which is set from bedroom count under the state code, plus the retention time the code requires. It is not set by the number of people currently living there.
Yes. The soil loading rate and the depth to the limiting layer are the inputs the dispersal sizing is calculated from, so a design produced before the evaluation is provisional.
Usually. Design flow is driven by bedroom count, so adding one changes the flow the system has to be permitted for.
From the Census ZCTA-to-place relationship file, with the share of Story City’s land area that falls in each. A ZIP is not a place boundary and the two only ever partly agree, which is exactly why both pages exist.
Straight-line distance from the Census internal point of Story City.
Parcel Perfect generates a code-shaped septic design and as-built style drawing for a parcel from the records and site data we hold, and shows every parcel we have classified as septic or sewer on one map. Both are open to use for any parcel in Story County, Iowa.