The depth is ever changing for River Thames. Opposite Southend, the depth is 11 meters; at Tributary the depth is about 9.8 meters; at Woolwich the depth is about 6.5 meters and at London Bridge the depth is 1.8 meters.
the best accurate. In the estuary the charted depth (which can for most general purposes be considered as the depth at low water) is about 20 metres at its deepest . To get the depth of water at Mean High Water Springs (MHWS) you can add about 5 wiki.answers.com