This is an English locational surname. Well recorded in the city of London since at least Stuart times, it presumably originates from a place called 'Salt waella' or similar, from the pre 7th century Olde English 'salt' meaning salt or a salt maker, and 'waella', a spring or tributary of a river. However although there are many places in England associated with salt making, such as Salt in Staffordshire, Budleigh Salterton in Devon, and Saltwood in Kent, there is no recording of Saltwell that we are aware of in any surviving gazetter. This would suggest that the surname originates from a now 'lost' medieval village. Whilst unusual, this is by no means uncommon, and it is estimated that at least five thousand surnames of the British Isles do derive from such places. As to why they 'disappeared' has been the subject of several books, but changes in agricultural practice, increasing urbanisation, and the effects of the Great Plagues of the 14th to the 17th century, are usually given as the causes. Early examples of the surname recording include Anne Saltwell who married Thomas Downham at the church of St James, Dukes Place, Westminster, on March 10th 1690, and George Saltwell who married Elizabeth Harrison, at St George's Chapel, Mayfair, on September 30th 1753.