Feddersen (F/43 no year) has a tracing board which he says is a French board for the 5th degree of the Ancient and Accepted Scottish Rite. Besides the well, the board also features the Vessel with Rams.
The short French ritual “Les Antipodiens” (see gun) has an explanation for the well:
The well means that when the brethern finished their labors, they were sanctified.
The fifth degree in the Francken Manuscript actually describes the well:
Mahabon on company with the 15 masters that wree chosen to attend him in this search, first went to the Temple, where seeing that blood had been spilt in many places of it, he at last traced it to the well, in the north part of the Temple, when he immediately concluded that H.A. had been killed there, & perhaps flung in the well. thus prompted and further encouraged by the appearance of a Luminous light or meteor standing over the well, he determined to have it drawn dry; this being done, he went down in it, bur found not the body, as he expected but was lucky to find the masters Jewel […]
Quite a different explanation from sanctification or purification!
A 29th degree Ancient and Accepted Scottish Rite tracing board speaks of: “a well for purification”.
On a French tracing board in Les Francs Maçons Écrasés (1747) a tracing board is described as containing two “lavoirs”, ‘washing places’. See wheelbarrow (the two dark spots left and right of the mosaic pavements are the “lavoirs”).
I can imagine the fountain having a similar symbolism.
Top: Dąbrowski P. 212. Year and designer unknown.
Bottom: Feddersen (Die Arbeitstafel in der Freimaurerei Band I (1982) F/43, P. 313) gives as source Maurerisches Handbuch, 1829 (first edition 1821, this is a translation of Manuel Maconnique Ou Tuileur De Tous Les Rites De Maconnerie Pratiques En France by C. Vuillaume, 1820)