London Overground operates a train from Harrow on the Hill to Watford every 20 minutes. Tickets cost $2 - $5 and the journey takes 18 min. Alternatively, Transdev PLC operates a bus from Harrow on the Hill to Watford every 10 minutes. Tickets cost $11 and the journey takes 35 min.
From Harrow & Wealdstone train to Watford Junction. 18 min £2. From Harrow-on-the-Hill Underground Station Tube to Watford Underground Station. 20 min £3. From Harrow Town Cen Sheepcote Rd line 258 bus to Watford High Street Railway Station. 35 min £7. From Harrow on the Hill taxi to Watford. 13 min £31. From Harrow on the Hill drive to Watford. 13 min £1. From Harrow on the Hill walk to Watford. 2 h.