The River Ching originates in Epping Forest

Epping Forest

Epping Forest is an area of ancient woodland in south-east England, straddling the border between north-east Greater London and Essex. It is a former royal forest, and is managed by the City of London Corporation....

, and runs to the River Lea, but not before being severely polluted in its lower reaches. It is damned twice, the first time to form Connaught Water, in the parishes of Loughton

Loughton

Loughton is a town and civil parish in the Epping Forest district of Essex. It is located between 11 and 13 miles north east of Charing Cross in London, south of the M25 and west of the M11 motorway and has boundaries with Chingford, Waltham Abbey, Theydon Bois, Chigwell and Buckhurst Hill...

 and Waltham Abbey

Waltham Abbey, Essex

Waltham Abbey is a market town of about 20,400 people in the south west of the county of Essex, in the East of England region. It is about 24 km north of London on the Greenwich Meridian and lies between the River Lea in the west and Epping Forest in the east. It takes its name from The Abbey...

, and again at Highams Park

Highams Park

Highams Park is a district in the London Borough of Waltham Forest, England, adjacent to Epping Forest. The forest at Highams Park contains a boating lake formed by Humphry Repton after damming the River Ching. There are parks and basic shopping facilities such as Budgens, but no major supermarket...

. The river runs through Chingford

Chingford

Chingford is a district of north east London, bordering on Enfield and Edmonton to the west, Woodford to the east, Walthamstow and Stratford to the south and Essex to the north. It is situated northeast of Charing Cross and forms part of the London Borough of Waltham Forest...

, however the name of the river is in fact a back-formation

Back-formation

In etymology, back-formation is the process of creating a new lexeme, usually by removing actual or supposed affixes. The resulting neologism is called a back-formation, a term coined by James Murray in 1889...

from the name of that area, rather than the town being named after the river.