A horizontal shower replaces the bathtub in this futuristic six-square-metre home spa, designed for small-space living by German studio Sieger Design.

Realised in collaboration with bathroom brand Dornbracht, the Small Size Premium Spa, which the company refers to as SSPS, has been designed in response to urbanisation and shrinking apartment sizes.

"More and more people are moving into cities, resulting in increasing scarcity of living space and rising apartment prices. But at the same time, there's increasing demand for enhanced quality of life," said Michael Sieger, co-founder of Sieger Design.

"The bathroom is becoming ever more important as a part of overall living space. Not only does it serve to prevent illness and boost quality of life, but it is also becoming more and more of a refuge – a place to refresh and revitalise."

"The Small Size Premium Spa, SSPS for short, fulfils all the standards of a luxury spa in a compact area of approximately six square metres," he added.

The minimalist design is divided into a dry zone and a wet zone, which are separated by a glass screen. The wet zone features a vertical and a horizontal shower with customisable integrated strip lights, and spotlights, sound system and fragrance options.

"Since the innovative shower applications make it just as comfortable to shower lying down as to take a bath, there's no need for a bathtub," said Sieger.

"If a bathtub is expressly required, it can be precisely integrated (in combination with a footbath, for example) and covered when necessary so that it can be used as a seat."

Meanwhile, the dry zone features a double washbasin with an extendible sprinkler head that can be used to wash hair. A compact toilet sits in the corner, while a display built into the mirror or cabinet front allows users to individually control all elements of the bathroom. As the room is fully networked, it can be configured remotely ahead of time via an app.

Mirrors are used to create a feeling of spaciousness. A large screen that lines the wet zone acts as a virtual window, which can display a live camera feed of the surroundings and produce an atmosphere that harmonises with changes in the natural light outside.

The SSPS concept was originally debuted in 2015. It is on show at the West One Bathrooms showroom in Battersea, London.

Since then, Sieger Design has also introduced a slightly larger eight-square-metre version for hotels called the SSPS Suite.

This year, it unveiled the SSPS Apartment – a concept for a 35-square-metre city home that features an integrated private spa, including a 3.5-square-metre washing and showering area.

The bath is located behind a translucent glass barrier that lets in daylight from the living area. In addition to the Vertical Shower and the rain panel integrated into the ceiling, the wet zone features special massage jets positioned to stimulate various parts of the body.

Additional electronically controlled water outlets enable residents to programme automated sequence showers while sitting, or they can select a "stimulating leg shower". While the bathroom is occupied or during the spa treatments, the apartment's separate guest toilet can be used at any time by others.

The apartment also features a compact seven-square-metre kitchen and plenty of built-in floor to ceiling storage. Functions, materials, finishes and colours can be tailored to meet individual needs and taste.

The design team said the concept could be used not only for private flats, but also for hotels or yachts.