Watermills, Owned by the Lord, a Licence to Print Money

In medieval England, most watermills belonged to the lord of the manor. Since he had the monopoly, the lord would charge everyone a fee to grind their own corn. The many monasteries that populated the land also built and owned watermills.

Owning a mill in medieval England could make your very wealthy. For some lords or ‘mill barons’, this could have enormous economic value.

Ridley watermill
Ridley watermill

It is said that the De Veres family who were based in Castle Hedingham, had a portfolio of 17 mills. Most mills were in existence before the  Domesday survey of 1086.


Watermills are one of earliest known power sources and the first that was not generated by animals or man. They are exactly what the name suggests – mills that are powered by water.

The flow turns a wheel that uses the water’s energy to perform a mechanical operation which can grind grain, drive saws, power lathes or forge bellows, move pumps or run textile mills. The water then goes back into the river or stream below the mill.

Watermills & Medieval Europe

Throughout medieval Europe the water mill was the main power source. This didn’t change until the invention of the steam engine and the Industrial Revolution.

Towns that were close to water became hives of industry at the expense of some cities, as power centres shifted from urban to rural areas. As goods began to be made in greater numbers, but at a lower cost, new markets started to appear where they could be sold.

Overshot water wheel, applied for watermilling since the 1st century BC

In turn the increased output meant more demand for raw materials, which local  merchants were happy to supply. Their wealth and the wealth of the town would increase, which in the Middle Ages meant better protection and a safer home.

How Watermills Works

Water-powered mills operate by a simple process. Water is channeled towards the wheel which is turned by the flow. The power this generates is transferred to a drive shaft which in turn moves a piece of equipment.

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Initially this would have been millstones to grind grain, but the technology gradually progressed to include other types of tools.

The wheel itself sits either vertically or horizontally. The earliest mills in Europe used the horizontal wheel and some still survive in the Orkneys and Shetland, where they are known as Clack or Norse mills.

There are two basic types of watermills, one powered by a vertical-waterwheel via a gear mechanism, and the other equipped with a horizontal-waterwheel without such a mechanism. The former type can be further divided, depending on where the water hits the wheel paddles, into undershot, overshot, breastshot and reverse shot waterwheel mills.

They lie flat on the water and are attached directly to a drive shaft. When the wheel turns, so does the shaft. They’re not particularly efficient and vertical wheels soon developed, which required different engineering, as they use cogs and gears to transfer the power generated to the mill.


Vertical wheeled mills are typically arranged so that water hits the paddles, enabling it to be either undershot or overshot. An undershot wheel sits directly in the stream and relies on the force of the water to push it.

This means that when the water levels are low and flow is weak, little power is generated. An overshot wheel is more efficient and these were introduced in medieval times.

Interior of the Lyme Regis watermill, UK (14th century)

With an overshot wheel, the force of gravity is used to help drive it, so there is less dependence on the volume and pressure of the water. A flume or pipe channels the water to the wheel, where it is then dropped directly onto the paddles.

As the wheel spins, it drives the shaft. The ways in which the power created was utilised was starting to become increasingly complex by the late Middle Age as the technology developed.


The method of grinding grain between two stones was quickly adapted for water mills. The bottom millstone is fixed, while the top one is powered by the wheel and can be moved up and down to regulate the coarseness of the grain being milled.

A pair of millstones

Both stones are corrugated, so the grinding motion of the top one crushes the grain to the required consistency. A hole in the top stone allows more grain to be added as required. In the final process, sieves are used to produce a fine flour.

Cistercian Monks

The monastic order of Cistercian Monks was founded in 1098, which was just after water wheel technology had established itself throughout Western Europe. St Bernard, who took over the order, seized on the water mill as a way for the monks to gain their financial independence.

At the time of the Domesday Book in 1086 there were two watermills in Dunster. One which was called the Lower Mill was on the site of the present mill. In the 17th century there were both malt and oats mills but by 1721 one of these had been converted to a fulling mill

Fifty years later, the Cistercian order led the way in water power and agricultural technology. Monasteries were built where flowing water could be diverted to run through them and to drive waterwheels.

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The power produced was used for milling, forging metal, wood cutting and making olive oil. The same water source provided for other needs such as drinking and washing, then took sewerage with it as it flowed away.

The Domesday Book

Dating watermills is often a difficult task. Mills can be on the same site for hundreds of years, with rebuilding, restoration and repair work inevitably taking place over that time. Consequently a watermill that looks eighteenth or nineteenth century could have an interior which is much older.

Mapledurham Watermill
A watermill was already present at Mapledurham at the time of the Domesday Book.

The Domesday Book records around six thousand operational mills in 1086, with that number doubling over the following two hundred years. Many of these are subsequently documented in various sources, before starting to appear on maps.

Tidal Mills

In coastal areas the power of the sea was harnessed by Tidal Mills. These were much rarer than mills on rivers, but they continued to be used until recent times. The earliest known tidal mill was excavated at Nendrum in Northern Ireland and was built for an early Christian monastery around 620.

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Like the railway in the nineteenth century and the internet in the twenty first, watermills didn’t just change lives during the medieval period, they changed the way of life for whole communities and were a precursor to the Industrial Revolution.

For the men who built and operated them, there were significant savings in terms of both time and money. More work could be done in considerably less time at a lower cost with less people. Now, by using the power generated by a water wheel, one man could do a job that had previously required many.


Fulling is a process in woven cloth-making, particularly wool, that gets rid of oils, dirt and other impurities, as well as shrinking the cloth by the use of friction and pressure.

Alresford – Fulling Mill
This Alresford fulling mill dates from the 13th century. A fulling mill was used to pound wet woolen cloth after it was woven thus making it shrink and tighten. Image Credit: Chris Talbot CC BY-SA 2.0

The end result is a water-repellent, smooth, tight fabric; duffel cloth as used in duffel coats being a good example. Before mills this was done by stamping on the cloth or hitting it with bat, which was very labour intensive and took time.

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The fulling mill saw the same task being completed by wooden hammers powered by the waterwheel and one man who made sure that the cloth was moving through the mill machinery properly.

Mill Ponds

Just as a windmill requires wind to move the sails and is redundant on calm days, water mills need a constant flow of water to turn the wheel. As such some smaller rivers just weren’t up to the job because of the variable volume of water.

Flooding after heavy and consistent rainfall has been a hot news topic in recent years, but once the runoff has been carried away, the decline in level can be dramatic. The flow of water also changes from season to season. It’s heaviest in winter and in a dry summer river water levels can become very low, which is not good news if you’ve got a mill to run.

Cogglesford Mill, Lincolnshire
Cogglesford watermill, Lincolnshire

But even the busiest mill didn’t need a constant stream of water, twenty four hours a day. A steady flow during working hours would do just fine – so the solution was a mill pond. The pond would be filled by the flow of the river when the mill wasn’t operating. With the water stored, it could now be released when required.

Several Hours of Operation

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Mill ponds were created by building a dam or weir across the waterway, but water could also be diverted to a mill pond by a man-made stream.

The flow of some rivers was never enough to turn the wheel, so the mill was entirely dependent on the water saved up in the pond. When the pond was full, the mill would be able to operate for a few hours and then the process would have to start all over again.

Larger faster flowing rivers might have had many mills along their length, so the one highest up river would have a limit on how much water it could store in its pond.

Cromford mill pond
Cromford mill pond

Those further downstream would continually have their ponds topped up during the day by the water being released from the ponds of the higher ones. But when the working day was over, the downstream mill had to wait until all the ponds above them were full and overflowing, before there was enough water for their own.

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Many bodies of water still carry the name mill pond today, even though the mill itself has long since disappeared. Watermills were the main power source for industry until the invention of the steam engine. The technology was continually improved, with the mechanised gearing process becoming increasingly complex.

So much so, that the technology was later adapted, scaled down and used in clocks and similar mechanical devices.

Watermills Today

The days of the watermill aren’t yet over. Some that survive have had turbines installed to generate clean electricity and others are now lived in as homes. There are also the mills that are still in operation, but as a working museums.

The watermill at Calbourne on the Isle of Wight has been supplying flour and animal feed to the local population since the time of the Domesday Book. Still producing up to sixty tons every year, it is open to the public during the summer.

Ilfield watermill is the only one in West Sussex that is still powered by it’s original water source, the Ilfield mill pond. It is open to visitors on selected Sundays during spring and summer.

Wherever you live, there is probably a watermill close enough for a visit and it’s well worth the effort, as they all offer a real glimpse back into the past.