Harptree aqueduct photos from Grace's Guide.
If I got something else wrong, you can make a pull request on github.
Please note the transcript should reflect what I say in the video, even if that turns out to be wrong. So if the transcript is not what I say, pen a PR to fix it, but if my narration was wrong in the first place, open a PR to add an erratum in this section of the page instead.
As someone who grew up in a developed country in the 20th century, I’m quite guilty of taking this for granted.
I’ve spent a fairly significant amount of time nerding out over railways and metro systems, bridges, skyscrapers and the like, but the engineering that brings drinkable water directly to my tap is not something I’d previously given much thought to.
However, while looking at some maps of my region for interesting places to walk, I discovered something unusual near a village called Winford, about six miles south west of Bristol. Popping out of nowhere was an aqueduct, rather incongruously striding across the Somerset sheep-farming countryside beside a medieval church before promptly vanishing back into the earth again.
So, I started digging, and it turns out my mains water supply has a rather more interesting backstory than I’d ever imagined.
However, I’ll just quickly apologise in advance that I have a lot of imagery of the aqueducts, and not that much info about them, whereas I’ve got not so much imagery to illustrate everything else in the story, so this video might be a bit visually disjointed as I pad it out with aqueduct footage while talking about other things.
Anyway, let’s start with a little historical context. The main driver in this story is a simple one: population growth. The population of Bristol grew from about 27,000 in 1700 to somewhere around 60 or 70,000 a century later, and by 1900 it was over 300,000. If a city’s population increases by 10 times in the space of two hundred years, it stands to reason that its demand for water will also increase tenfold - if not more.
Why more? Well, Wikipedia pointed out one of those things which should have been glaringly obvious to me, but somehow I’d never really thought of - ships docking at a port need to restock on supplies for the crew’s next voyage, including fresh drinking water. So, the construction of the floating harbour in 1804 to 1809, a harbour which could and did handle more ships than before, further added to the demand for water.
You might think, then, that throughout the 18th century and up to the mid 19th century, Bristol saw a steady stream of civil engineering projects to make the water supply bigger and better, providing a rich narrative for me to relate here. But you’d be wrong. After a scheme was completed in 1698 to bring water from Hanham Mills, for the next 140 years, essentially nothing happened. In fact, the Hanham Mills scheme was so badly mismanaged it ended up going bankrupt in 1782; still the authorities did nothing.
In 1811 an act of parliament was granted for the construction of a canal and water supply system from the Kennet & Avon Canal, but this found no funding, and yet another three decades slipped past without any significant development in Bristol’s water system.
By the 1840s this neglect was seriously catching up with the town. In 1844 a Royal Commission was formed to investigate the state of England’s large towns, and in 1845 they issued the damning verdict: “Viewed as a sanatory [sic] question, there are few, if any, large towns in England in which the supply of water is so inadequate as at Bristol.”
I tracked down the full report, thanks to the Wellcome Collection who have made the whole thing freely available as a pdf. I’ll be honest, I expected a 500-page report from a committee of Victorian civil servants to be stultifyingly dull, but it turned out to be surprisingly entertaining.
Enlisting the expertise of a Mr Samuel Stutchbury from the Bristol Institution for the Advancement of Science and Art to help them with their hydrological enquiries, the Commission reported that “probably [...] not more than 5000 persons, and these constituting the most wealthy families in Bristol and Clifton, are supplied with water by means of pipes laid on into their houses. On this supposition, 73,443 persons are wholly dependent on supplies obtained by public or private wells.”
It seems astonishing to me that wells could possibly have sustained 70,000 Bristolians, but apparently medieval and early modern Bristol was particularly flush with wells and springs, such that even by the 1840s the main problem was not an insufficient quantity of water per se, but the quality of the water and the cost and inconvenience of accessing it.
The report reels off a list of public wells, noting that “These are not all strictly public wells, but there seems no check to the use of any of them; and some such as those in Wine Street, the Pithay, St Peter’s pump &c., are in constant use by the public”.
St Peter’s pump was built into a well located on Peter Street, just next to St Peter’s Church, so obviously the well is called St Edith’s Well. The pump was installed in 1633 although the well itself is many centuries older. Following recent archaeological work the well is now visible through a circle of glass. The decorative stone cross built above the well can also be viewed today, provided you don’t mind travelling some 40km to the country estate of Stourhead, in Wiltshire. But that is a story for another time.
Medieval Bristolians didn’t simply make do with taking water from wherever wells happened to be located, either. They had an extensive system of conduits channeling it from springs and sources to more convenient locations. For example, check out this fountain on the corner of St Mary Redcliffe churchyard. In itself, it is neither particularly old (dating from 1932), nor useful (since no water emerges from the lion’s mouth these days), but it marks the point where water was historically stored in giant tank, freely accessible by the public, at the end of a conduit running from Rugewell in Knowle, a couple of miles away. This water source was given to the city by the Knowle landowner Robert of Berkley in 1190, as the plaque commemorates, and over 800 years later there’s still an annual tradition of walking the entire length of the route to check the pipe… but that too is another story.
The essential point that our Royal Commission was keen to emphasise was that while Bristol was plentifully stocked with wells and conduits like these, from which the general public could draw water freely, the system was nevertheless entirely inadequate for a modern industrial city.
One problem was that while the water itself may have been free, getting it to the home was not, requiring either the expenditure of significant time and effort carrying buckets etc, or else paying a going rate of 3 shillings per week for water-carriers to do that labour for you. The Report noted that this was very inefficient compared to towns such as Preston or Nottingham, with their shiny new Water Companies, who charged only 1 or 2 shillings per household per week. The extra work and/or cost involved in Bristol inevitably resulted in poorer Bristolians being distinctly miserly with their water usage when it came to cleaning their clothes, their homes and themselves, with negative consequences in terms of public health.
The aversion to washing was compounded by the fact that most of the water was too hard to work properly with the soap of the time. And that was hardly the worst of the public health concerns. There was essentially no attempt at a proper sewage system, so waste regularly contaminated wells and groundwater. To quote our Report again, “in some courts of the Temple and other districts little care is taken to prevent the filth of the gutters from oozing into the wells; and in one place, in the Dings, we observed a privy immediately adjacent to the well”.
The Commissioners conclude that “From the evidence which has been lain before this Commission, it has been shown that the labour and consequent expense attached to the system of obtaining a supply of water from draw-wells or pumps engenders filthy habits, directly acting upon the health, and indirectly upon the morals of the people.”
The Victorian moralising goes on at some length, as you might expect, but I will resist the temptation to smirkingly quote it, and instead point out that this moralising was based on perhaps surprisingly scientific grounds. The report notes that Bristol had a mortality rate of 3.1 percent, compared to an notional average of more like 2%, resulting in an excess mortality of 3083 deaths over the past five years. It was deemed the third unhealthiest town in England, after only the notoriously overcrowded industrial towns of Liverpool and Manchester, and the Report goes to some length quoting local doctors and surgeons in support of the idea that this could be directly tied, at a district-by-district level, to the deficiencies of the water and sewerage systems.
This, then, was the mountain of evidence which finally convinced people that Something Must Be Done, and on 16 July 1846, an Act of Parliament duly established the Bristol Waterworks Company. This group had defeated a rival scheme from the Merchant Venturers Company, who intended to tap the springs at Hotwells to supply affluent Clifton, but had no interest in providing for the broader population of urban Bristol, with their more ambitious proposals to bring water from the Mendip Hills, more than 10 miles to the south.
The chief engineer behind this project, dubbed the ‘Line of Works’, was James Simpson. Simpson was already an experienced civil engineer, and something of a specialist in this sort of work, being chief engineer of both Chelsea and Lambeth Water companies in London, pioneering the use of sand filtration systems and also being entrusted with the task of kitting out Windsor Castle and other royal palaces with modern plumbing.
His challenge was to convey water from the springs at the source of the River Chew, about 120m above sea level, to a reservoir built at Barrow Gurney. This is about 14km or 9 miles as the crow flies, but since his conduit was entirely gravity based it followed the contours of the land to some extent, resulting in a total length of 18km or 11 miles.
This doesn’t sound very far to modern ears, and in fairness when you look at what British canal engineers were doing in the era, it wasn’t particularly far even for the time. However, from a viewpoint on Dundry ridge, just slightly south of Bristol, you can see almost but not quite the whole route, and I find looking at this way gives a certain sense of scale that maps and words do not.
The springs, by my reckoning, are located somewhere up here, from which the conduit runs somewhere roughly in this direction, and then over here… and then somewhere over here… and by the way I do mean *roughly*, because working out exactly the course it takes and presenting it in 3D is far beyond my patience and abilities, but anyway, somewhere over here… then you can see one of the aqueducts here, then it carries on over here before reaching the other visible aqueduct here, and we’ve still got a couple of kilometers before we reach the reservoirs, out of frame to the right.
Let’s head down to the village of Winford for a closer look at these aqueducts.
The one near the church is officially listed under the catchy name of ‘AQUEDUCT TO EAST OF CHURCH OF ST MARY AND ST PETER’. Completed in 1851, it’s about 260 metres in length, carrying an ovoid pipe about 1.4m high and 1m wide constructed from riveted plates of wrought iron, carried on rocker bearings atop limestone piers.
Limestone is a traditional local building material, so the piers fit into the landscape easily enough, but the wrought iron pipe is another matter. To me, it somehow manages to look slightly science fiction and futuristic even at the ripe old age of 170.
It’s probably not too much of an exaggeration to say that at the time, it actually was technologically futuristic. Although wrought iron was a well-established material for the construction of things like steam boilers or ships’ hulls, using it for bridges or aqueducts like this was absolutely cutting edge. Robert Stephenson’s Britannia Bridge and Brunel’s Chepstow Railway Bridge, opened in 1850 and 1852 respectively, are typically cited as the major innovators in wrought iron tubular bridge construction, so James Simpson’s work here would seem to be quietly pioneering.
Presumably this is what the Historic England listings mean when they assert these to be “probably the earliest example of such engineering”, without qualifying what they mean by “such engineering”. I surely don’t need to point out that all kinds of ancient civilisations built sophisticated water distribution networks and aqueducts many thousands of years ago, so I can only assume they refer to the use of wrought iron specifically.
At each end the pipe vanishes into a limestone revetment wall, and at each end the earthwork is topped with a shaft access structure. Roughly following the course of the conduit upstream from here, these shaft constructions crop up every few hundred metres. They vary in shape, some round, some square; all are individually numbered.
It’s not a very long walk through this very pleasant Somerset farmland before you reach the second aqueduct, also completed in 1851. This is essentially the same design as the first, which is unfortunate for me, because it leaves me with nothing much more to say about it, and thus justify rolling out all my footage of it, although it is arguably the more picturesque of the two. Certainly I found the sheep grazing between the piers to be more photogenic than the intrusive clutter of modern barns seen at the one near the church.
As before, both ends vanish into revetment walls with access shafts on top. The limestone piers are the same design and the wrought iron seems to be from the same manufacturer too, with the same riveting and the same sized plates (about 5ft). By the way, I should point out that this iron pipeline does not continue through the cut-and-cover tunnelled sections of the conduit - those were constructed from masonry.
The most obvious difference between the two aqueducts is that this one is painted more of a yellowy beige colour. It is also noticeably taller than the previous one we saw. I can’t find any official sources on their heights, but judging by the contour lines on maps, this one runs between 10 to 15 metres above the valley floor as opposed to 5 to 10 metres. It’s almost exactly the same length though, at around 260m or 825ft.
The central pier is described by Historic England as “cruciform, with raking buttresses”, appearing from a distance as a chunky pyramid. The extra buttressing is because this is the fixed point of the pipe: the bearing here is subtly different, more constrained than those on the other piers. Again, the other aqueduct is of exactly the same design in this regard, although it’s harder to see since there the central pillar is masked by trees.
South of this viaduct is a rare example of the Line of Works being clearly visible in one of its non-aqueduct stretches. Well, clearly visible if you already know what you’re looking at, anyway. Here, a smaller, shallower valley has been spanned with the cheaper and easier means of building an earth embankment. And just in case you worried this might be an unrelated disused railway or something, another shaft structure confirms we’re on the alignment of the water system.
For most of the next 10km or so, though, the route is mostly invisible bar the shaft structures. There are a couple of notable exceptions. At Harptree Combe there is a third aqueduct, although I should really describe that one as the first aqueduct, since it is both the first the water travels across, and was also the first to be built, being completed in 1849. I didn’t make it that far, but can use these photos thanks to the good people of Grace’s Guide.
To the untrained observer you can see that it is once again of essentially identical design; however to the trained eyes of the Grace’s Guide author, it is meaningfully different to the other two, with longer wrought iron plates (about 9 foot 6) and different rivets, possibly suggesting the ironwork was manufactured and assembled by somebody else.
The final extremely visible aspect of the Line of Works is an obelisk on Breach Hill. Frustratingly, 90% of sources on the internet copy-paste the same mildly inaccurate line of text, saying it is “said to be a waterworks marker”. Even more disappointingly, the origin of this sentence appears to be the official Historic England listing for the obelisk.
In fact, it is not merely a marker, but serves an important functional purpose. The conduit has an average gradient of around 10 inches per mile (16 cm per km), but the gradient is not consistent, and has some minor ups and downs along the way. Breach Hill is the high point, meaning that an air bubble could form here, either blocking flow entirely or creating an inconsistent flow with the resulting phenomena such as water hammer almost guaranteed to split the pipe.
The obelisk, then is actually a ventilation outlet to ensure no such air lock could form at this high point. It was reportedly given this monument-like styling to satisfy the landowner.
Again you can see it is individually numbered, and if like me you are slightly slow on the uptake, you might briefly find yourself puzzled why the high point is marked with a sign saying ‘LOW’, until you realise that’s not LOW, that’s L.O.W., for Line of Works.
The natural neat narrative way to wrap up this story is to return to where I started, with a shot of a tap, and the triumphant pronouncement that the Line of Works is still in active use today, and as such, some of this very water travelled here through these very aqueducts. (Quietly ignoring the fact the tap is stock footage shot by someone in France.)
This is true in theory, although the full story is slightly less romantic. It only took a few decades for the Barrow tanks - covering about 50 hectares - to become insufficient to quench the ever-growing city of Bristol, and in 1898 the Bristol Waterworks company set about damming the Yeo to create the 180-hectare Blagdon Lake. By the 1930s they needed to add Cheddar Reservoir, 105 hectares, and in the 1960s these were dwarfed in turn by Chew Valley Lake, at 490 hectares the fifth largest artificial lake in England. This is not to even mention their sources and reservoirs to the north of the city.
So put in that context, the amount of Bristol water supplied by the Line of Works is statistically very small, and I suppose only a very small fraction of my glass of water made its way to me over those sheep and past that church. Still, it’s a nice thought, and either way, it certainly beats having to carry myself a bucket full of sewage and cholera back from the well.
That’s all for this video. If you want to go and see the aqueducts for yourself, there are plenty of public footpaths in the area, from which all of this footage was taken. So there’s no need to get special permission or pay any sort of entry fee, but it is private working farmland, so be respectful of livestock, stick to the paths, and all that.
Special thanks to the Parental Taxi, Picnic and Engineering Consultancy Services for helping make this video possible. As usual, thanks also to all the people who have provided freely reusable photos, scanned documents, textual information and so on - in this case I leaned particularly heavily on Grace’s Guide, as well as the Wellcome Trust’s digitized version of the Royal Commission report, as well as the usual suspects like Wikipedia and Openstreetmap.
And, as always, thanks for watching. If you enjoyed it, please subscribe for more videos like this. Cheers.