Island Barn Reservoir covers 49 hectares (122 acres) just south of the Thames at West Molesey, Surrey. It is enclosed by artificial banks and has the River Ember running to its south and east and the River Mole to its west and north. The reservoir lies within the Borough of Elmbridge and is managed by Thames Water.

Address for navigation purposes: Ray Road, West Molesey, Surrey KT8 2LF (Map:; OS grid reference TQ139670)

History[edit | edit source]

In 1900 the Lambeth Waterworks Company obtained an Act of Parliament authorising the construction of a reservoir on farmland known as The Island because it was surrounded by the courses of the Mole and Ember rivers. The company acquired the land but did not start work on the reservoir. In 1904 the company was taken over by the newly formed Metropolitan Water Board. New legislation in 1907 allowed the board to begin construction on 24 October 1908, the work being carried out by Robert McAlpine & Sons. The reservoir was officially opened on 4 November 1911. It gets its name from Island Barn Farm, which was demolished during construction.

Habitat[edit | edit source]

The reservoir has a capacity of 4,5000,000 cubic metres (nearly 1,000 million gallons) of water, which is drawn from the River Thames. The average depth is about 24m (80ft or 13 fathoms). The water is contained by an artificial embankment with a circumference of 2.7km (1.7 miles), which was constructed from 1.25 million tons of earth taken from the inside of the reservoir. The gently sloping inner side of the embankment is lined with concrete slabs. Since the reservoir is used by Thames Water only as a back-up, it tends to remain full.

Species[edit | edit source]


The reservoir is know for rare grebes, sea ducks and divers in winter and for waders on passage and in winter.

Further information needed, please

Other vertebrates

Foxes are known to patrol the banks, and the occasional grass snake has been seen. No anglers to recognise fish, but Stickleback, Perch and Pike have both been spotted.

Further information needed, please


Gammarus (presumably G Pulex) common, and also Zebra Mussels. Freshwater sponges seem common.

Further information needed, please

Practicalities[edit | edit source]


The nearest railway station is Hampton Court (trains from Waterloo), from which there is a walk of about 2km; alternatively, alight at the previous station, Thames Ditton, and take the 514 bus to Island Barn Road. The 514 also serves Surbiton station.

Train: from Hampton Court train station cross Hampton Court Road to Creek Road for 411 bus stop. Take this bus and get off at War Memorial (5-10min journey) and walk down Walton Road and turn left down High Street which bends to the right and passed a sports ground/school, keep going into Approach Road, follow this short culdesac and you will see large metal gate with Molesey Heath sign on it (10min walk). Enter and walk straight across the field and up slope onto top of the heath/scrub, follow path to the left and you'll see the reservoir to the left (5min walk) There is only one spot from Molesey Heath that gives the best vantage point over the embankment to the water with limited view. This is not signposted and anyone new to this site will have to find the spot, that gives the best view, by trial and error. I am suprised that a special viewing platform hasn't been built to give a better view over the reservoir similar to the one at Morden Hall Park - as the view you get will depend on your physical height. Larger birds can be seen with binoculars but scope recommended for distance involved. Michael Mac - March 2020


Access is officially by Thames Water permit only. There are no longer permits and there is no access.


The Island Barn Reservoir Sailing Club offers lunch, snack and drinks to its members and their guests. Does anyone know whether birders (with or without permits) have access to these facilities? (Answer - I'm sure we wouldn't mind if you asked nicely!)

This page has been cobbled together from various internet sources by someone who has never visited the site but thinks that it deserves a page on this website because it keeps cropping up on the Latest News page. If you are familiar with the site, please correct, expand and/or update this information (and delete or amend this paragraph).

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