A vast, white, pristine building sits on a dusty main road, about 250km south of Istanbul. Deep inside its briskly air-conditioned interior, past several rounds of security gates, is a soundproof chamber where a lone toilet sits on a raised platform. On either side are a pair of ultra-sensitive microphones mounted on adjustable stands. The toilet looks like it is under interrogation.

Suddenly, it erupts in a flush. Scientists study computer screens. One declares the noise level to be about a seventh of a standard flushing mechanism. We are witnessing “one of the quietest toilets in the world.” His colleagues nod sagely.

Welcome to the VitrA Innovation Campus in the town of Bozüyük, home to the Turkish sanitary-ware manufacturer’s laboratories, where experts strive to gain an advantage in the fast-paced global high-tech loo market. The security, together with the centre’s no-photos-in-the-labs policy, are evidence of just what a competitive business this is.

Today the team is demonstrating VitrA’s latest “powerful-yet-silent” technology, the Quantum Flush, launched in the UK this year and — the R&D team are keen to point out — the only one on the market with a Quiet Mark, the independent global certification. VitrA joins brands including Switzerland’s Laufen, Belgium’s Ideal Standard and Germany’s Grohe in the race to persuade consumers to enter a new world of whisper-quiet toilets.

Modern high-tech toilets are ever more complicated, sophisticated and increasingly global as manufacturers try — with some success — to persuade US and European households to replace their bog-standard loos with the kind of luxury, feature-enhanced “smart” versions that are part of everyday bathroom life in Japan.

VitrA’s experts work not only on flush acoustics but also on a dizzying array of novelties: ceramics with advanced hygiene surfaces, remote-control lids, heated seats, inbuilt bidet functions, water efficiency, and more. The latest models come with separate, programmable water-jet settings for male and female bodies.

Irem Turkucu, VitrA’s product manager, explains that the VitrA model’s quietness was achieved by directing flush water in a smooth circular motion, rather than allowing it to splash about, randomly generating a lot of noisy turbulence “so the molecules are not clashing with each other.” The team conducted 70 “computational fluid dynamic analyses” lasting four days each, he tells me, and built about 16 different prototypes.

The global smart-loo market was worth $1.5bn in 2021 and is predicted to reach $2.6bn by 2028 according to data by IMIR — relatively small, but fast growing. Europe and US sales are expected to rise significantly, partly due to hygiene awareness (a pandemic legacy) and rising elderly populations. And partly down to aspiration: “life-changing” is how one Brit describes his new Japanese loo, swiftly installed after a trip to Tokyo.

But can more westerners be persuaded to spend $2,000 or more on a souped-up loo, when a luxury “standard” version costs about a quarter of the price? Kazuki Osugi, general manager in Europe for Toto, one of the biggest and most venerable names in Japanese toilet tech, whose Neorest WX1 retails for in excess of £10,000, thinks so. He points out that the UK is the spiritual home of toilet innovation (rudimentary flushing versions first appeared 430 years ago and commercial models were widely sold by the late 19th century).

“Our founder [Kazuchika Okura in 1917] came to Europe and was impressed, so our Japanese toilet really started in Europe,” he says. “The toilet was invented in the UK, so we think the country that invented it might like to use our products.”

Toto says its “Washlet” — a lavatory with built-in bidet, also known as a “shower toilet”, first manufactured in 1980 but only released to the market in Europe in 2009 — “disrupted the industry.” “When we joined [the European market] there was no demand, or even awareness,” says Osugi. Washlet iterations come with all sorts of innovations, from adjustable bidet-spray cleansing patterns (oscillating, pulsating, and so on — much like a garden hose spray gun) to self-cleaning technology.

Toto’s global smart toilet sales climbed to nearly 60mn units a year by August 2022 (the latest available) from about 17mn 20 years earlier. At the company’s sleek showrooms in London, customers can test out the pleasures of warm seats and integral night-lights (for navigating a dark bathroom in the middle of the night). Inevitably, “wellness” is a big part of its message.

“A family trip to Japan in 2015 was an eye-opener,” says Alex Evans, director of Washloo, a UK company set up to offer “high-quality bathroom experiences” to British consumers. “There was this realisation of how much we missed and the lack of products — a gap that needed filling.” The company offers loo features such as LED displays, warm-air dryers, and automatic opening and closing of lids when users enter the room, though “everyone likes a heated seat,” says Evans. Sales have doubled in volume year on year, he says, despite the hefty prices.

Back at VitrA’s innovation centre, an ominous sign outside a side-laboratory reads “Simulated Observation Room.” Here, volunteers test trial models for everything from sizing to convenience before being quizzed by behavioural scientists. No cameras, I’m assured — instead, the guinea pigs “describe their toilet experiences.”

What sort of customer wants a quiet loo? The team tells me the Quantum Flush was developed partly in response to rising numbers of affluent young professionals working from home in the post-pandemic world.

I wonder if the real purpose of all this research is to allow remote workers to take calls in the bathroom, but the researchers (looking faintly horrified) explain their intention is to prevent tell-tale sloshing sounds in adjacent rooms from seeping into video meetings. No one on a Zoom call wants to hear a colleague’s loud, turbulent loo gurgling in the background, they explain.

It looks like sales of smart loos will not be going down the pan anytime soon.