Fully marked & marshaled trail races over 10k and Half Marathon distances

10k and Half Marathon distances on the glorious trails and tracks surrounding Grafham Water.

Race information

Starting and finishing at Marlow Park, Grafham Water, the 10k race provides the perfect introduction to trail running whilst the half marathon provides a decent challenge for those looking to go further or build their experience of trail running.

The routes enjoy the best of the Cambridgeshire countryside as well as having some fantastic views of the reservoir.

Entries

Minimum age for entry on race day is 16 years old for the 10k and 17 years old for the half marathon.

The race cut off time is 4 hours for both races.

As the races use footpaths across farmland, running with dogs is not permitted.

Entries, and transfer of entries, will close 7-days before the event.

New for 2027!

Race Harborough Water Trail Race Series

Our Pitsford Water Trail Races have been a popular fixture since launching in 2024, and in 2026 we brought the same 10k and half marathon format to Grafham Water. In 2027, we’ll complete the series with the introduction of our third venue at Rutland Water!

Runners will have the chance to take on all three events as part of the series (and we’ve got an exciting medal design in the works!). There will also be a little extra to race for, with trophies awarded to the fastest male and female runners across all three events in both the 10k and half marathon distances. The winners will be presented with their trophies at the final event of the series in 2027.

The series consists of each of the 10k or half marathon races at:

– Pitsford Water Trail Races (Sunday, 7th March)

– Rutland Water Trail Races (Sunday, 11th July)

– Grafham Water Trail Races (Sunday, 10th October)

Start time/location

Race HQ, the start and finish, will be at Marlow Park, Grafham Water, Grafham, Huntingdon, Cambridgeshire. PE28 0BH.

Registration will be open from 07:00 for participants to collect their race numbers, timing chips and pre-ordered race t-shirts.

The half marathon will start at 09:00.

The 10k will start at 09:15.

The routes

Both routes will be fully marked with arrow signs.

10k: Download GPX (right click, save link as)

Half Marathon: Download GPX (right click, save link as)

Both routes leave Marlow Park, heading West in the direction of Easton, picking up the trails and sections of the Three Shires Way long distance bridleway. The 10k loops back round onto the outward bound track, whilst the half marathon route continues with a large lap of the reservoir.

No in-ear headphones will be allowed at this event. Headphones that work by conducting sound through bones and do not sit in the ears are allowed.

On-course support

As with all Race Harborough events, there will be professional first aid on hand at the start and finish with the ability to access runners on the course. Race Harborough volunteers will also be on-course to provide hydration at 3 water stations on the half marathon route (3.4, 5.7 and 10 miles) and 1 water station (5.1k) on the 10k route. Water will also be available at the finish.

Kit

Trail shoes are advisable, or shoes with some grip.

Mandatory items:

Full charged mobile phone including the numbers of the Race Director and Race Medic (half marathon)

Our races are cupless, so you will be required to bring your own cup

Whilst the above are the only mandatory items, you may also like to consider the following depending on the weather conditions on race day.

Waterproof jacket

Long sleeved base layer

Hat and gloves

Prizes

There will be prizes for top 3 male and female finishers in both races, and all finishers will receive a specially commissioned race medal.

Supporters

The best place for your friends and families to support you is alongside the tracks at Grafham Water. Whilst the half marathon route does run through a number of local villages, these villages are small and have very little parking (other than that for the villagers themselves) so we would ask that any support is limited to the tracks alongside Grafham Water in order to maintain the support of the event from the local villages. You could always offer to volunteer and support all runners on route!

Free race photos!

As with all Race Harborough events – you don’t pay for your race pics! Free digital downloads of your race are available to download soon after the event finishes and we’ll announce their availability on our Facebook page.

Charity

For 2027, the main focus of our charity support will continue to be the Jubilee Foodbank, Market Harborough, and the Weston Favell Centre Foodbank, Northampton. Everyone who enters a Race Harborough event will be given the opportunity to make a donation to support these good causes and, we hope, our event community will rise to the challenge and help make a difference to those that need it most.

Latest updates

For the latest updates about this and other Race Harborough events, please Like & Follow the Race Harborough Facebook page.

Course Records

10k - Charlie Wyeth, 44:49 (2026) and Nadine Clemo, 52:46 (2026)

Half Marathon - Daniel Koch, 1:26:13 (2026) and Elizabeth Mckinlay, 1:33:28 (2026)

Description supplied by the event organiser.