How to Build a Natural Earthen Forest Pool
Excavate, shape, and seal a primitive natural plunge pool in forested soil using hand tools, river stones, and a compacted clay lining for water retention.
- Read the tools, materials, safety notes, and steps below for free.
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- Allow camera and microphone. Point your phone at the work; the coach watches your progress and tells you the next step.
🧰 Required Tools & Equipment
- ✓ Mattock or trenching pick
- ✓ Pointed digging shovel
- ✓ Heavy wooden hand tamper
- ✓ Carrying buckets or baskets
- ✓ Smooth river stone (burnishing tool)
- ✓ Bamboo splitting knife or machete
📦 Materials & Supplies
- ✓ High-plasticity natural clay
- ✓ Smooth river stones and boulders
- ✓ Coarse gravel for drainage spillway
- ✓ Bamboo or hollowed logs for aqueduct piping
⚠️ Safety Checkpoints & Warnings
- • Ensure pool walls are sloped or stepped rather than vertical to prevent wall collapse during excavation.
- • Verify no major tree roots (>5cm diameter) are severed, which could destabilize nearby live trees.
- • Ensure safe footing and proper lifting posture when moving heavy excavated clay and river rocks.
- • Incorporate a dedicated overflow spillway to prevent uncontrolled erosion and muddy washouts.
📋 Step-by-Step Guide (6 Steps)
Clear and Mark Basin Perimeter
Select a shaded, flat to gently sloping forest area away from high-traffic root zones. Clear away surface leaves, twigs, and loose topsoil down to solid earth, then outline a 3-meter wide oval perimeter using stakes and scored ground lines.
- • A crisp, bare earth boundary clearly visible with dark organic topsoil pushed 1 meter outside the work zone.
- • Building directly under large dead tree limbs (widowmakers).
- • Failing to clear loose forest duff, which contaminates the later clay layers.
Excavate the Basin and Terraced Steps
Dig out the central pool area down to a depth of 1.2 to 1.5 meters using a mattock and shovel. Carve two wide underwater steps along one side at 40cm increments to allow safe entry and structural wall support.
- • A stepped amphitheater-style hole with firmly defined bench tiers and loose dirt hauled clear of the rim.
- • Digging perfectly sheer vertical dirt walls that crumble under foot traffic.
Tamp and Compact the Excavated Subsoil
Pound the base floor, bench tiers, and sloped walls repeatedly with a heavy flat-ended wooden tamper. Work in concentric passes until the exposed soil produces a solid thud and leaves no footprint indentations.
- • Uniform, hard-packed earth with no soft crumbly pockets across the floor and terraces.
- • Leaving loose, aerated dirt at the floor-wall corners.
Apply and Burnish the Puddled Clay Liner
Hydrate stockpiled raw clay into a workable, sticky paste and apply a continuous 5-8cm thick layer over the entire floor, steps, and walls. Smooth and compress the wet clay with palms and a flat river stone to eliminate all air bubbles and fissures.
- • A seamless, slick, mirror-smooth clay skin covering 100% of the earthen basin without exposed dirt patches.
- • Applying clay too dry, which causes rapid shrinkage and spiderweb cracking.
Set Stone Coping and Entry Steps
Embed smooth, interlocking river stones into the wet clay along the rim and step treads. Press them firmly into the clay bed so half their profile is anchored, creating erosion-resistant stepping surfaces and stabilizing the perimeter.
- • Even rows of rounded river stones firmly seated into the clay along the pool edge and submerged steps.
- • Using jagged, sharp stones that can cut bare feet or puncture the clay base.
Install Gravity Water Feed and Overflow Spillway
Split bamboo or hollow small logs lengthwise to form an elevated water flume leading from an upstream source into the pool rim. Carve a stone-lined overflow trench on the downhill side leading water safely away from the pool structure.
- • Fresh water cascading cleanly into the basin from the flume while excess water exits through the rock-lined spillway.
- • Omitting an overflow drain, causing water to overtop raw dirt edges and wash out the pool walls.
Credit: inspired by an original tutorial by Primitive Tool — watch the original on YouTube.
Don’t have everything?
- No Natural clay soil? Sodium bentonite clay powder mixed into local sandy subsoil
- No Bamboo poles? Hollowed-out split pine logs or flexible polyethylene drip tubing
- No Wooden hand tamper? Flat-bottomed heavy rock or a concrete paver tied to a timber pole