How the Modern Waterbed Works
A 1971 patent describing a liquid-filled, heated furniture support designed to cradle human bodies without letting them touch the bottom of the container.
Original patent title: “Liquid support for human bodies”
A 1971 patent describing a liquid-filled, heated furniture support designed to cradle human bodies without letting them touch the bottom of the container. Granted to Innerspace Environments Inc in 1971 with 9 claims and 70 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
The patent describes a furniture support, specifically a sofa or bed, that uses a flexible, inelastic bladder filled with liquid to support multiple people. The system requires a rigid frame to hold the liquid and prevent the sides of the bladder from bulging outward. A key feature is that the bladder is filled completely, leaving no air inside, which allows the surface to conform to the body's shape while ensuring the person remains suspended by the liquid. It also includes an optional heating element to keep the liquid at a comfortable temperature and solid particles like styrofoam to stop the liquid from sloshing around when someone moves.
The gap
What does this patent NOT cover?
- Does not cover air mattresses or inflatable supports that rely on gas rather than liquid.
- Does not cover waterbeds that allow the user to touch the bottom surface (the patent requires the body to be supported entirely by the liquid).
- Does not cover flexible bladders that are not contained within a rigid lateral framework.
- Does not cover liquid supports that contain significant amounts of air within the bladder.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The invention solves the 'bottoming out' problem by using a rigid frame to force the liquid to support the body's weight, and it uses internal particles to dampen the wave motion that would otherwise make a multi-person bed unstable.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Traditional hardside waterbeds
Heated liquid-filled furniture
Medical fluid-support mattresses for pressure sore prevention
Why it matters
The bigger picture
This patent is a foundational document for the commercial waterbed industry, which saw a massive surge in popularity during the 1970s and 1980s. By defining the specific requirements for a stable, heated, and comfortable liquid-support system, it helped transition the waterbed from a niche DIY experiment into a standardized piece of home furniture.
Filed
July 27, 1970
Granted
June 15, 1971
Market context
Who's building on this
Companies in this space
The original assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, Innerspace Environments, helped establish the early market. Today, the technology is largely maintained by specialized bedding manufacturers who focus on therapeutic and orthopedic sleep solutions that utilize fluid-based pressure redistribution.
Market impact
This patent helped legitimize the waterbed as a viable consumer product, leading to a boom in furniture manufacturing during the late 20th century. It set the design standards for safety and comfort that allowed the industry to scale beyond hobbyist designs.
Claim 1 — Plain English
What this patent covers
The patent describes a furniture support, specifically a sofa or bed, that uses a flexible, inelastic bladder filled with liquid to support multiple people. The system requires a rigid frame to hold the liquid and prevent the sides of the bladder from bulging outward. A key feature is that the bladder is filled completely, leaving no air inside, which allows the surface to conform to the body's shape while ensuring the person remains suspended by the liquid. It also includes an optional heating element to keep the liquid at a comfortable temperature and solid particles like styrofoam to stop the liquid from sloshing around when someone moves.
The clever bit
The invention solves the 'bottoming out' problem by using a rigid frame to force the liquid to support the body's weight, and it uses internal particles to dampen the wave motion that would otherwise make a multi-person bed unstable.
What it does not cover
- Does not cover air mattresses or inflatable supports that rely on gas rather than liquid.
- Does not cover waterbeds that allow the user to touch the bottom surface (the patent requires the body to be supported entirely by the liquid).
- Does not cover flexible bladders that are not contained within a rigid lateral framework.
- Does not cover liquid supports that contain significant amounts of air within the bladder.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Moderate
Citation count
37/40
Highly cited
Claim breadth
6/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$59K – $190K
Midpoint $119K · expired or expiring · industry ×2.2
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
9 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Hall, C. P. (1971). How the Modern Waterbed Works (U.S. Patent No. 3,585,356). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3585356/waterbed-liquid-support
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How the Modern Waterbed Works cover?
A 1971 patent describing a liquid-filled, heated furniture support designed to cradle human bodies without letting them touch the bottom of the container.
Who owns patent US 3585356?
Innerspace Environments Inc owns this patent, granted in 1971.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 3585356 cited by?
This patent has been cited by 70 later patents that build on its ideas.
What problem does this patent solve?
This patent is a foundational document for the commercial waterbed industry, which saw a massive surge in popularity during the 1970s and 1980s. By defining the specific requirements for a stable, heated, and comfortable liquid-support system, it helped transition the waterbed from a niche DIY experiment into a standardized piece of home furniture.
What does this patent NOT cover?
Does not cover air mattresses or inflatable supports that rely on gas rather than liquid.
Patent monitoring