Bristol Water is a British water company which supplies 266 million litres of drinking water daily to over 1.2 million customers in a 2,600 km² (1,000 sq mi) area centred on Bristol, England. It is regulated under the Water Industry Act 1991. Sewerage services in the Bristol area are provided by Wessex Water.

Approximately half the water is taken from the Mendip Hills, particularly Chew Valley Lake, Blagdon Lake, Cheddar Reservoir and Barrow Gurney Reservoirs, with the other half piped from the River Severn via the Gloucester and Sharpness Canal. There are 6,772 km (4,208 mi) of local water mains.

In June 2021, Pennon Group acquired Bristol Water for $563 million.

During the medieval period, Bristol had a remarkably efficient water supply, as there were a large number of wells and springs, and most streets had a wooden trough into which water was discharged. The troughs were supplied by local priories, as most of the wells and springs were also owned by religious foundations, but with the Dissolution of the Monasteries between 1536 and 1541, maintenance and upkeep of the system passed to parishes. As the population increased, they proved inadequate and started to become polluted. The first Bristol Waterworks Company was set up in 1695, and obtained water from Hanham Mills, on the edge of the city limits, which was piped into the main part of the city in hollowed-out elm pipes. The scheme was completed in 1698, but never worked well, as the company was not well organised or managed, and it gradually got into serious debt. The Corporation of Bristol were unwilling to take over the scheme, and the company became bankrupt in 1782.

The need for fresh water increased significantly between 1804 and 1809, when William Jessop carried out work to improve the facilities of Bristol Harbour, known as the Floating Harbour because water levels were unaffected by the tides. Large numbers of extra ships used the facilities, and needed their water tanks to be filled before putting back out to sea. There was an idea to build a canal from the Kennet and Avon Canal near Bath into Bristol, which would be used by boats and also as a water supply channel, but that scheme failed due to lack of funds after obtaining an enabling act of Parliament, the Bath and Bristol Canal and Bristol Waterworks Act 1811 (51 Geo. 3. c. clxvii). A commission was appointed in 1844 to consider the state of large towns in England, and reported that Bristol was one of the worst large towns in respect of water supply. Most water came from wells, the water was hard, making it unsuitable for washing, and the difficulty of obtaining the water meant that it was used very sparingly.

By the spring of 1845, there were two groups attempting to supply Bristol with water. The Merchant Venturers Company had proposed a scheme to supply the area of Clifton with water from two springs on the banks of the River Avon. Although that scheme had not been authorised in 1842, their proposal was to extend it, and they had enlisted the support of Isambard Kingdom Brunel as engineer. Edwin Chadwick and Thomas Hawksley had failed to persuade them that they should implement a combined water supply and drainage scheme, as just supplying water often led to worse sanitary conditions, with cesspits overflowing if there was no network of sewers to carry waste away. The second group proposed bringing water from the Mendip Hills and other springs in Somerset, and after some consideration of various engineers at a meeting held in the Bristol Corn Exchange on 20 June 1845, appointed James Simpson, based on his wide experience of water supply projects. In the ensuing parliamentary battle, the second group won, becoming the Bristol Waterworks Company.

The company, formally known as Bristol Waterworks Company, was formed on 16 July 1846 by the Bristol Waterworks Act 1846 (9 & 10 Vict. c. ccxxii). The first general meeting was held in the White Lion Hotel on Broad Street, when members of the first committee included William Budd, a physician who helped control cholera outbreaks in Bristol, and Francis Fry of the Fry family, better known for producing chocolate. The 1846 act authorised the construction of Simpson's "Line of Works", an 11-mile (18 km) aqueduct designed to carry water from Chewton and Litton to Barrow Gurney. A network of open-jointed drains and culverts were constructed at Chewton and Litton, to collect water from springs, which were located at a level some 400 feet (120 m) above that of Bristol Harbour. These fed into an egg-shaped masonry culvert, which followed the contours of the land for 2.25 miles (3.62 km), and was built by the cut-and-cover method. This fed into a tunnel cut through a ridge of magnesium limestone conglomerate, after which a rivetted wrought iron tube carried the water over the Harptree ravine. This section is 350 feet (110 m) long, and is carried on stone piers nearly 60 feet (18 m) above the valley floor. There are three further tunnels, with a combined length of 2.75 miles (4.43 km), two more wrought iron sections to cross ravines, both 825 feet (251 m) long, and 4.25 miles (6.84 km) of 30-inch (76 cm) cast iron pipes. The pipes had an average gradient of around 10 inches per mile (16 cm per km), but the gradient was not uniform, and there was a high point on Breach Hill Lane, to the south of Chew Stoke. To prevent an air lock forming, an open vent was constructed, sufficiently high to ensure that water could not escape through it, and a stone obelisk was constructed around it, standing 50 feet (15 m) high.

A reservoir was constructed at Barrow Gurney to receive the water, and because the springs at Chewton were the source of the River Chew, the company was required to build three compensation reservoirs, so that the flow in the river could be maintained. Two were constructed at Litton, with a third on the Winford Brook near Chew Magna. Water was fed into the supply system from three service reservoirs. Cotham reservoir was fed by gravity from Barrow Gurney, and some of its water was then pumped to Durdham Down reservoir, which was outside the city limits at the time. The third reservoir at Bedminster Down supplied the district to the south of the harbour, and was fed by gravity from Cold Bath spring, a little to the west of Barrow Gurney. The construction work was finished in 1851, and was designed to deliver 4 million imperial gallons (18 Ml) per day, but by 1860 the company had realised that this was not achievable in dry years.