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FernwaterONSITE SYSTEMS

Clean water, returned to the ground.

Fernwater designs, installs and inspects onsite wastewater systems for the Fern River valley. Engineered from the soil up by a soil scientist, built to be quiet, and kind to the wells and streams around them.

Book a site assessment(555) 014-2018
Ferns in soft morning light at the edge of a wood
The wood below our test site at Alder Hollow, where the drain field meets the ferns.

A septic system is a small water treatment plant that happens to live under your lawn. The soil does most of the work. Our job is to understand the soil.

Dr. Elin Moss, soil scientist and founder

A field guide

How the water moves

Nobody sees an onsite system working, which is the point. Here is what happens to every gallon, from the kitchen sink to the water table. Choose a stop to follow it.

How the water moves through an onsite systemA cross section of a property. Water leaves the house, rests in a buried septic tank, is cleaned again in an aerated treatment unit, is dosed into gravel trenches in the drain field, filters down through several feet of soil and rejoins the groundwater.TopsoilUnsaturated subsoilGroundwater

Swipe the drawing sideways to follow the pipe.

Three things we do, and do carefully

We do not run a pumping fleet. We design systems, install the ones that need more than a tank and a trench, and tell buyers the truth about the one they are buying.

01System design and permits

From $2,800

For new builds, additions and replacements. We start in the ground, not at the drawing board.

  • Test pits and a soil log by a soil scientist, with a percolation test where the county asks for one
  • A stamped system design sized to your bedrooms, your soil and your setbacks
  • The county permit application, written and filed for you, and every question from the reviewer answered
  • Installer walkthrough on day one, and a final inspection before the trench is closed

Design in two to three weeks. Permit times vary by county, typically four to eight weeks.

02Advanced treatment units

From $18,000 installed

For thin soil, high groundwater, small lots and lakefront property, where a tank and a trench are not enough.

  • An aerobic treatment unit or media filter chosen for your site, not from a single catalogue
  • Pressure-dosed drain field, so the soil receives small, even doses all day
  • A quiet blower in an insulated housing, sited away from windows and terraces
  • Two years of service visits and the maintenance reports your county requires

Installed in four to seven working days once the permit is issued.

03Inspections for home sales

$450

For buyers, sellers and their agents. A clear answer before closing, in writing, within 48 hours.

  • Tank located, opened and pumped with a licensed partner so baffles and walls can be seen
  • Hydraulic load test and a probe of the drain field for ponding and saturation
  • A plain-language report with photos, the system’s age and design, and what it will need in the next five years
  • A phone call to walk you or your agent through it

Booked within five working days. Report within 48 hours of the visit.

Water droplets on a fern leaf

Every system we design is checked against one question: would we be happy to drink from the well downhill of it?

Selected sites

What the ground looked like, what we built, and how it turned out. The landscape is the finished product: a good system leaves nothing to see.

A quiet house above a mown meadow, where the drain field now sits

A farmhouse above the meadow

Alder Hollow

Soil
Silt loam over clay at 30 inches
System
Replacement tank, pressure-dosed trenches
Result
Field placed on the only well-drained rise
Reeds and still water in a wetland below a lakeside lot

A lakeside lot beside the reed bed

Heron Lake

Soil
Sandy, with the water table at 26 inches
System
Aerobic unit and a shallow mound
Result
Nitrogen down 64% at the first county sample
A clear stream running over stones below a new build

A new build above a trout stream

Millbrook

Soil
Shallow loam on fractured rock
System
Media filter and drip dispersal
Result
Permitted at the 100 foot setback
Rolling green farmland in the valley

Six cottages on one shared field

Fern River valley

Soil
Deep, well-drained glacial till
System
Cluster system with one treatment unit
Result
Half the field area of six separate systems

Building a house, or buying one

For builders and owners

Call us before the house is placed on the lot, not after. A test pit on day one decides where the drain field can go, and the field often decides where the house should.

  1. 1Site visit and test pitsWithin two weeks of your call
  2. 2Design and permitStamped drawings, filed with the county
  3. 3Install and final inspectionCoordinated with your builder’s schedule
Start with a site assessment

For buyers and agents

A failing drain field can cost more than the kitchen you were planning to redo. Our inspection tells you how the system is doing and what it will need, in time to negotiate.

$450
Flat fee, pumping arranged
5 days
To your inspection visit
48 hours
From visit to written report
1 call
To talk it through with you
Book a home sale inspection
Dr. Elin Moss taking field notes in the wood

The practice

Dr. Elin Moss, and a spade

Elin spent nine years mapping soils for the state before she started Fernwater in 2011. She holds a doctorate in soil science and has logged more than 2,400 test pits across the valley, most of them by hand.

She still digs the first pit on every design job herself. The rest of the practice is small on purpose: two designers, one install crew we trust completely, and a service technician who knows every treatment unit we have ever put in.

A handful of dark loam from a test pit
Licensed designer
Lic. #000000 (sample)
Installer
Lic. #000000 (sample)
Counties
Alder, Fern River, Heron Lake, Millbrook, Ashby, Kettle Ridge

Notes from clients

Sample reviews, written for this concept.

Two other designers told us the lot could not be built on. Elin dug three test pits, found a strip of good soil we did not know we had, and the permit came back first time.

Hannah and Theo R., new build at Heron Lake

I send every buyer with a septic system to Fernwater. The reports are clear enough to read at the kitchen table and firm enough to negotiate with.

Marcus L., real estate agent

We barely hear the blower and we have never smelled a thing. The yearly report arrives before the county has to ask.

Priya S., advanced treatment unit, Millbrook

Start with the ground

Tell us about the property and what you are planning. We reply within one working day with a time for a site visit, or a date for your inspection.

(555) 014-2018

Monday to Friday, 8 to 5. Site visits across the valley.

We reply within one working day.