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well apparently Hawaii County decided to be more inclusive than the State mandate.
from a real estate agent's article I found it says AG land is included....
- In Hawaiʻi county, the new ordinance allows these ADUs in [b]Residential (RS), Duplex (RD), Residential-Agricultural District (RA), Agricultural (A), and Family Agricultural (FA) zoning districts[/b]. The State law only said “residential” zoning.
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Let's call the 512 sq ft house, House #1 and the new home, House #2. I assume that new House #2 will require a septic system. Will the OP be re-routing the waste pipes from House #1 into the septic system? Getting that approved would be a priority.
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The septic is up to the health department and if the septic is correctly sized it is allowed.
Septic tank size is determined by the total number of bedrooms.
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The new house will be in the back of my lot so too far away, plus it is about 50 ft higher in elevation, so no way to route the old house drain into the new septic system.
I am assuming they will not make me convert it when building the new house.
I need to review the codes again, I know it says any new construction needs a sepic system and also I believe it says if you add and addition to an exsiting house.
But I would think the current law that says you have until 2050 to convert a cesspool would still apply to the old house since I am not doing any work on that house.
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03-02-2025, 07:26 PM
(This post was last modified: 03-02-2025, 07:27 PM by Hotzcatz.)
![[Image: 13feb1.jpg]](https://hillsidefarmhawaii.com/pages/construction/2025pics/2feb2025/13feb1.jpg)
We have the same situation of the new ohana behind and above the existing house. (it looks huge but it's mostly lanai and the interior square feet is less than the house in front) We just had the septic installed in front of the existing main house and the ohana is attached to the same new septic system.
Pretty much any time you do anything to a lot that has an existing cesspool they want you to upgrade everything to septic. If you can get both houses on one septic, go for it. Will save a lot of bother later and save having to put in two septic systems.
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