I've read Bryson's book, and while I don't have enough background to debate that specific point, he usually invests a significant portion of time into research. It looks like he chose to compile some excerpts from it into an article for Daily Mail https://www.dailymail.co.uk/femail/article-1281933/Deadly-be...

Relevant quotes are toward the end:

"Well, until the mid-19th century, bathrooms were a rarity. Indeed, for 600 years most people didn't wash, or even get wet, if they could help it.

'Wash your hands often, your feet seldom, and your head never' was a common English proverb. In 1653, John Evelyn, the diarist, noted a tentative decision to wash his hair annually.

Robert Hooke, the scientist, washed his feet often (because he found it soothing), but appears not to have spent much time damp above the ankles. So most people fought dirt and odour by either covering it with cosmetics and perfumes or by just ignoring it.

Where everyone stinks, no one stinks. But, then, in the 18th century, suddenly water became fashionable, though only in a medicinal sense. Spa towns cropped up all over the country, and people started adjusting to the idea that they might now safely get wet from time to time.

Washing for the sake merely of being clean was remarkably slow in coming, however. When John Wesley, the founder of Methodism, coined the phrase 'Cleanliness is next to Godliness' in 1778, he meant clean clothes. With respect to bodily cleanliness, he recommended only 'frequent shaving and foot washing'.

What really got the Victorians to turn to bathing, however, was the realisation that it could be gloriously punishing.

Many diaries record how people had to break the ice in their washbasins in order to ablute in the morning. Rev Francis Kilvert noted with pleasure how jagged ice clung to the side of his bath and pricked his skin as he merrily bathed on Christmas morning in 1870.

Showers, too, offered great scope for punishment, and were often designed to be as powerful as possible. One early type was so ferocious that users had to don protective headgear before stepping in lest they be beaten senseless by their own plumbing.

Increasingly, bathrooms - albeit shared and down the corridor - became standard in hotels, and hoteliers who failed to heed this trend paid a hefty price. Nowhere was that more memorably demonstrated than at the vast Midland Hotel at St Pancras Station in London. Designed by the great George Gilbert Scott, the Midland cost the equivalent of £300 million when it opened in 1873, and was a wonder in almost every way.

Unfortunately, Scott provided just four bathrooms to be shared among 600 bedrooms. Almost from the day of its opening, the hotel was a failure.

In private homes the provision of bathrooms was hit and miss. The rich proved unexpectedly reluctant to bring them into their lives.

' Bathrooms are for servants,' sniffed one English aristocrat. In existing houses, bathrooms usually took the place of a bedroom, but sometimes were jemmied into alcoves or corners. Baths tended to be of exceedingly variable sizes.

A bath at Lanhydrock House in Cornwall was so big that a stepladder was needed to climb into it. Others, with showers built in, looked as if they were designed to wash a horse. Moreover, baths were still extremely expensive. A bath alone could easily cost more than £100 in 1910 - a price well beyond most households.

The British journalist, Katharine Whitehorn, recalled that, as recently as the late 1950s, she and her colleagues on the magazine Woman's Own were not allowed to do features on bathrooms. Why? Because not enough British homes had them - and such articles, it was felt, would only promote envy."