By Kjel Jones, independent septic & site-services researcher for Island Park · licensed Idaho real estate agent, LPT Realty

Published 2026-09-02

Two ways to bend a septic rule. One is ten percent; the other is a public proceeding.

The rules bend in two quite different ways

Sooner or later a site fails a number by a small margin, and the question becomes whether the number is negotiable. In Idaho it can be, and the rule provides two separate routes. They are not variations on one process. They differ in who decides, how long it takes, who has to be told, and how far the rule can move.

Getting the two confused is expensive, because the smaller route is fast and quiet and the larger one is neither.

The ten percent rule is the one most people need

The technical allowance is the modest route, and the modesty is written into it.

“The Director may make a minor technical allowance to the dimensional or construction requirements for a standard system if the allowance… does not affect adjacent property owners or the public at large; does not violate the intent of the rules; does not conflict with any other rule, regulation, standard, or ordinance; and changes to a dimensional requirement is not more than ten percent (10%) unless otherwise provided for in the TGM.”

— IDAPA 58.01.03, Individual/Subsurface Sewage Disposal Rules, section 010.01, Technical Allowance. Idaho Department of Environmental Quality. Rule text as amended 1 July 2025. Retrieved 1 September 2026

A change to a dimensional requirement is not more than ten percent unless the technical guidance manual provides otherwise, and that ceiling is the whole character of the route.

Ten percent is less than people hope for and more than they expect. On a hundred-foot separation it is ten feet, which is frequently the entire difference between a site that works and a site that does not. On a five-foot dimension it is six inches, which usually settles nothing.

The allowance is conditional on three things beyond the percentage, and all three have to hold:

• It does not affect adjacent property owners or the public at large.
• It does not violate the intent of the rules.
• It does not conflict with any other rule, regulation, standard, or ordinance.

That third condition is the one that quietly disposes of a lot of requests on the Island Park side of the county. A dimension can be adjustable under this rule and still be fixed by something else — a county provision, a subdivision covenant, another agency's standard. The allowance cannot be used to escape a requirement that comes from somewhere other than these rules.

What a variance petition actually has to contain

The petition route is a different animal. It is filed with the Director and has to include detailed statements describing three things.

• The facts on which the variance is requested — including the intended use of the property, estimates of the quantity of blackwaste or wastewater to be discharged, and a description of the existing site conditions.
• The reason the petitioner believes compliance would impose an arbitrary or unreasonable hardship, together with a list of the injury the variance would impose on the public.
• The precise extent of the relief sought.

The middle item is the one that surprises people. The petitioner is required to set out not only their own hardship but a list of the injury the variance would impose on the public. You are asked to make the case against yourself, in writing, as part of asking. A petition that describes only the applicant's difficulty has not answered what was asked.

The clocks are worth writing down, because two of them run before anything is filed. Property owners within 300 feet must be notified 15 days before the petition is filed, and evidence of that notice is submitted with it. Once filed, any person has 21 days to lodge a written objection, and a copy of any objection goes to the petitioner. The Director then has 60 days from filing to decide.

The three tests a decision has to satisfy

The rule constrains the decision itself, not merely the process. No technical allowance or variance will be granted unless all three of the following are true, and this applies to both routes.

1. Adequate proof is shown by the petitioner that compliance would impose an arbitrary or unreasonable hardship. The burden sits with the person asking, and the standard is not mere inconvenience or added cost.
2. What is granted is consistent with the recommendations of the technical guidance council or the technical guidance manual in use at the time of the petition. Note the timing — the guidance in force when you petition, not when the system was designed.
3. The Director has determined that approval will not violate the intent of the rules. The same intent test that governs ordinary approvals governs exceptions to them.

The decision comes back with reasoning attached. The Department provides the petitioner a description of the efforts made to investigate the facts alleged and to obtain and summarise the views of people who might be affected, a statement of the degree to which the Director disagrees with the facts as alleged, and any other facts believed relevant. A refusal, in other words, tells you which part of your account the Director did not accept — which is the useful half of a refusal.

How to tell which route you are in

1. Work out whether the problem is a dimension at all. The technical allowance reaches dimensional and construction requirements for a standard system. A problem that is not dimensional is not in scope for it.
2. Do the arithmetic. If ten percent of the number closes the gap, the small route may be enough. If the gap is larger, it will not be, and time spent pursuing it is time lost.
3. Check whether anything else fixes the same dimension. A county requirement or a recorded covenant is outside these rules and cannot be relieved by them.
4. If the petition route is required, identify every property owner within 300 feet before anything else, because the 15-day notice has to happen before filing rather than after.
5. Write the hardship case and the public-injury list honestly. Both are required, and the second is the one reviewers notice the absence of.
6. Expect the calendar to run to roughly three months from first notice to decision, and plan the build season around that rather than against it — the same seasonal squeeze that governs getting a site evaluation done in the first place.

The honest summary is that most sites never need either route, a fair number are solved by ten percent, and the petition exists for the genuinely difficult ground. Knowing which one you are in is worth more than hoping the number is negotiable, and it is a question worth asking before the permit application goes in rather than after it comes back.

Common questions

Can a septic rule be waived in Idaho?

There are two routes. A technical allowance is a minor administrative adjustment to a dimensional or construction requirement, capped at ten percent for dimensions. A variance petition is a formal process with public notice, an objection window and a decision deadline.

How much can a technical allowance change a dimension?

Not more than ten percent, unless the technical guidance manual provides otherwise. On a hundred-foot dimension that is ten feet; on a five-foot dimension it is six inches, which is usually not enough to matter.

Do neighbours have to be told about a variance?

Yes. Evidence must be submitted showing that all property owners within 300 feet of the affected site were notified 15 days before the petition was filed. The notice happens before filing, not after.

Can someone object to my variance petition?

Any person may file a written objection with the Department within 21 days after the petition is filed, and the Department provides a copy of any objection to the petitioner.

How long does a variance decision take?

The Director makes a decision within 60 days after the petition is filed. Adding the 15-day pre-filing notice period, the process runs to roughly three months from first notice to decision.

What has to go in a variance petition?

The facts the request rests on including intended use, estimated wastewater quantity and existing site conditions; the reason compliance would impose an arbitrary or unreasonable hardship together with a list of the injury the variance would impose on the public; and the precise extent of relief sought.

Do I really have to describe the harm my own variance would cause?

Yes. The rule requires a list of the injury the variance would impose on the public as part of the petition. A petition that sets out only the applicant's hardship has not supplied what the rule asks for.

On what grounds can a variance be refused?

It will not be granted unless the petitioner proves compliance would impose an arbitrary or unreasonable hardship, what is granted is consistent with the technical guidance in use at the time of the petition, and the Director determines approval will not violate the intent of the rules.

Can a technical allowance get around a county rule?

No. One of its conditions is that it does not conflict with any other rule, regulation, standard or ordinance. A dimension fixed by a county provision or a recorded covenant is outside these rules and cannot be relieved by them.