Heated Soaking Tubs: What They Are and How to Choose One

A heated soaking tub is a deep tub for sitting in hot water, without banks of massage jets. The idea comes from the Japanese ofuro: sit upright, water to the shoulders, stay still, get out. Outdoor versions are heated by wood, by electricity or both, and the modern one most people picture is a round cedar tub. What separates a soaking tub from a spa is not the heat but the depth, the quiet, and the absence of anything to do in it but soak.

What makes a tub a soaking tub

• Depth over length. A bath asks you to lie down; a soaking tub asks you to sit up with the water over your shoulders. That takes about 21 inches of water above the seat, which is why soaking tubs are tall and round rather than long and shallow. Every AlumiTub is 38 inches deep as standard, 44 or 48 on request, with 21.5 inches of water over the seat at the recommended fill.
• No banks of jets. Nothing pushing water at you, no bank of pumps to hear, no plumbing runs to keep clean. A wood fired soaking tub has no moving parts at all; an electric one has a single gentle 30 gpm jet, returning water from the filter circuit.
• Heat held rather than churned. The water is at 101 to 104°F and it stays there. On a wood fired tub with the lid on it loses only two to three degrees overnight; on an electric tub the heater holds the set point.
• Round, so everyone faces in. The social difference between a soaking tub and a spa: a circle of people looking at each other, or a row of seats facing the same way.

How heated soaking tubs are heated

Wood. The oldest way, and the Japanese goemonburo was heated this way for centuries. A firebox submerged in the water brings a Standard tub to temperature in about three hours with no electricity, and the fire is part of the soak. The Wood Fired.

Electric. A heater and filter in cedar steps beside the tub, on a 240V circuit, holding whatever temperature you set and running on a schedule, so the tub is ready at the hour you keep for it. The Electric.

Both. A Hybrid carries the firebox and the electric system, heats fast on wood and holds on electric, and keeps a weekly practice going through a fire ban. The heating options guide compares the three.

Materials: hinoki, cedar, and what holds the water

The classic Japanese soaking tub is hinoki cypress, an all-wood tub that seals by swelling and must stay full. Western versions use Western Red Cedar the same way, with the same rule. A cedar-clad tub with a marine-grade aluminum structure keeps the cedar for the scent, the look and the insulation, and lets the aluminum hold the water, so it can be drained between soaks, left empty through winter, and filled from a lake or the sea. Five things most buyers never know about cedar hot tubs covers the difference.

Choosing one

• Size by how many sit in it: 5 feet for two to four, 6 for four to seven, 7 for six to ten, depending on the heating system, with the full table in the dimensions guide.
• Heat by the site: wood if there is no power or the fire is the point, electric if the tub should be ready without you, hybrid if you cannot predict the next ten years.
• Depth by the soak: ask for water over the seat, not tub height. Anything under 20 inches is a bath, not a soaking tub.
• Weight by the base: 3,200 to 7,000 lbs filled. A patio carries it; a deck needs checking.

The ritual that goes with it, from the rinse before to the tea after, is in how to create an onsen style bath at home. Sizes, heating options and lead times are on the cedar hot tubs collection.

Common questions

What is a heated soaking tub?

A deep tub for sitting upright in hot water without banks of massage jets, after the Japanese ofuro. Outdoor versions are heated by wood, electricity or both, held at 101 to 104°F, and the defining feature is water over the shoulders rather than length to lie down in.

What is the difference between a soaking tub and a hot tub?

A soaking tub is a kind of hot tub. The distinction is jets: a spa has banks of them and the pumps that drive them; a soaking tub has none, or a single gentle one, so it is quiet, deep, and simpler to keep clean.

How is an outdoor soaking tub heated?

By a wood firebox submerged in the water, by an electric heater and filter beside the tub, or by both in one tub. Wood needs no power and heats a mid-size tub in about three hours; electric holds a set temperature on a schedule.

How deep should a soaking tub be?

Deep enough to sit upright with the water over your shoulders, which takes about 21 inches above the seat. AlumiTubs are 38 inches tall as standard with 21.5 inches of water over the seat, and 44 or 48 inch builds are available.