This uncommon name is of Anglo-Saxon origin, and is a topographical surname for someone who lived 'by the water', by a river or a lake. The name derives from the Old English pre 7th Century 'bi', Middle English 'by', by, beside, with Old English 'waeter', Middle English 'water', water, lake, stretch of water. A number of ancient English surnames are composed of similar elements, such as 'Byfield', for a resident near a patch of open land; 'Byford', for someone who lived by a ford; 'Bygrave', for someone living by a defensive ditch or dike, and 'Bytheway', for someone whose home was beside a main highway. Topographical surnames were among the earliest created, since natural or man-made features in the landscape provided easily identifiable distinguishing names among the small communities of medieval England. The marriage of John Bywater and Eleonar Copgood was recorded at St. Martin-in-the-Fields, London, on September 19th 1637. The first recorded spelling of the family name is shown to be that of Thomas Bithewater (witness), which was dated 1219, in the Yorkshire Assize Rolls, during the reign of King Henry 111, known as 'The Frenchman', 1216-1272. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.