Septic Installation & Cesspool Conversion in Mountain View
We install septic systems and convert cesspools in Mountain View, about 15 minutes up Highway 11 from our equipment yard in Keaau. Mountain View is older than the subdivisions around it, and the ground under the village is older too. That changes how a septic system gets designed here.
Mountain View by the Numbers
- 4,215 residents and 1,604 housing units in the Mountain View census area (2020 Census). That area covers about 55 square miles, so it takes in a lot of farm and forest land beyond the village.
- Steady growth: 2,799 people in 2000, 3,924 in 2010 and 4,215 in 2020.
- Elevation: about 1,434 feet at the village.
- Rain: the Mountain View rain gauge, at 1,519 feet, averages about 172.5 inches a year in the Rainfall Atlas of Hawaii, with records back to 1901.
- Lava hazard: the village area is mapped in Zone 3 on the USGS lava-flow hazard map. Check your own parcel, because zone lines don’t follow property lines.
- Rock: the village sits on Mauna Loa lava (the Kau Basalt), mapped at roughly 5,000 to 30,000 years old.
- Water: the county runs the Olaa-Mountain View water system, and many homes outside the village use rain catchment.
Older Ground, Deeper Soil
Much of upper Puna sits on 1400s lava with thin soil. The center of Mountain View is different. The USDA describes the Ohia soil series, which has its type location near Mountain View village, as volcanic ash over lava with 40 to more than 60 inches to bedrock. The mapped soil at the village is Ohia hydrous silt loam on 3 to 10 percent slopes.
What that means for your system:
- A real soil profile is more likely. State rules require the engineer to look at a 5-foot soil profile and run a percolation test. Near the village, that test hole may find soil for most of its depth, which can open up a conventional septic tank and leach field.
- The soil holds water. The USDA rates Ohia soil as moderately slow to drain, over very slow bedrock. Add 170-plus inches of rain and a perc test can come back slow, which usually means a bigger leach field.
- Rock still shows up. Where the engineer hits fractured lava inside that 5-foot profile, the rule calls for a soil replacement system with at least 3 feet of separation to groundwater.
- Gentle slope. On 3 to 10 percent slopes, leach lines follow the contour, and roof and driveway runoff needs to stay off the field.
Plantation Roots and the Homes They Left
The road from Hilo to the volcano, which passes through this area, was finished in 1894. Before 1900, coffee was the main crop in the Olaa district. Then the Olaa Sugar Company, founded in 1899, planted cane along both sides of today’s Highway 11 between Keaau and Mountain View. State maps of historical sugar lands show cane reaching the eastern edge of Mountain View in 1920 and 1937. The sugar mill, by then Puna Sugar, closed in 1984.
That history leaves a mixed housing stock, and a few kinds of projects come up again and again:
- Older village homes on cesspools. A house built before Hawaii banned new cesspools in 2016 may still be on one, and the older the house, the more likely that is. Conversion means pumping and backfilling the old pit, then installing a permitted system.
- Older, smaller parcels. If your lot was recorded before August 30, 1991, the 10,000-square-foot minimum per system doesn’t apply.
- Additions and ohana units. Any room of 70 square feet or more counts as a bedroom, and each bedroom adds 200 gallons per day to the design flow.
- New homes on outlying farm lots. New construction needs an approved wastewater system before the county permit is signed off. See our guide to septic requirements for a new home.
Working Around the Village
Getting an excavator here is a straight run up Highway 11. On site, wet ash soil gets soft and heavy equipment can rut a yard if the weather turns. Older lots often have tanks, buried water lines and outbuildings close to where the system needs to go, and a soil replacement bed needs room for fill trucks.
Rules and Money for Mountain View Owners
Act 125 requires every cesspool to be converted, upgraded or connected to sewer by January 1, 2050. A sale doesn’t trigger conversion, but DOH can require one after a permit adds bedrooms, or when a cesspool is pumped too often or overflows. Our Act 125 explainer has the details. To see how your cesspool is rated, use the UH Hawaii Cesspool Prioritization Tool. For sewer questions, ask the county Department of Environmental Management.
Most conversions in Hawaii run about $20,000 to $50,000. Deeper soil can help, but slow perc results push costs up. USDA Section 504 offers loans up to $40,000 at 1 percent for very-low-income rural owners, and grants up to $10,000 for owners 62 and older, so check eligibility with the USDA office in Hilo. The state loan fund created by Act 204 (2026) isn’t open yet; the Hawaii Green Infrastructure Authority expects a late 2026 launch. Our grants and loans page tracks changes.
Where Mauna Loa Meets Kilauea
Mountain View sits near a boundary you can’t see from the road. The state’s geologic map shows the village on Mauna Loa lava. A few miles south and east, Fern Acres, Eden Roc and Fern Forest sit on the Ailaau flows from Kilauea, dated to about 1410 to 1460 AD and fed by the lava tube system that includes Kazumura Cave. The USGS hazard map follows the same split: the village is in Mauna Loa’s Zone 3, the subdivisions mostly in Kilauea’s.
That’s why neighbors only a few miles apart can get very different soil reports. In the village, you’re more likely to dig into weathered ash. On the younger flows, rock tends to come up sooner and the design often turns to soil replacement.
Mountain View also shows up in county wastewater planning. In 2022, the county’s study of adding wastewater service in Puna named Mountain View among ten communities identified for some type of treatment, and the county accepted a programmatic environmental impact statement in October 2023. That study was at the feasibility stage and didn’t pick site-specific solutions, so don’t hold off on a needed conversion waiting for it. Check current status with the Department of Environmental Management.
Subdivisions Around Mountain View
Getting a Mountain View Project Started
If you have an older Mountain View home on a cesspool, or plan to build on a farm lot outside the village, we can walk the property and coordinate with your engineer. Request a free estimate
Frequently Asked Questions
Is the soil in Mountain View better for septic than in the nearby subdivisions?
Often, near the village. The Ohia soil there is ash over lava with 40 to more than 60 inches to bedrock, while the subdivisions to the south sit on much younger lava. Depth varies by lot, so the engineer’s 5-foot profile decides.
Does 170 inches of rain a year affect my leach field?
Yes. Wet ash soil can perc slowly, which usually means a larger field. Keep roof runoff and catchment overflow pointed away from it.
My plantation-era house is on a cesspool. Do I have to convert now?
Not because of its age. The deadline is January 1, 2050. DOH can require it sooner if a permit adds bedrooms, or if the cesspool is pumped more than twice or overflows more than once in 12 months.
My village lot is small. Can it work?
Possibly. If it was recorded before August 30, 1991, the 10,000-square-foot rule doesn’t apply. Setbacks still do: 5 feet to buildings and property lines, 9 feet to the line for a seepage pit.
Is county sewer coming to Mountain View?
The county’s Puna wastewater study listed Mountain View as one of ten communities for possible treatment, but the work was at a high-level stage. Ask the Department of Environmental Management before planning around it. Our step-by-step process guide covers what a conversion involves in the meantime.