What were ring wells?

Hint:Ring wells were constructed as pot rows, or ceramic rings placed on top of each other.
Ring wells were used as drains and garbage dumps . These were used as toilets, occasionally.

Complete answer:
Ring wells, so-called because of the lining with terracotta rings, have to be separated from other types of dug wells that can be narrowly divided into the following four classes, viz., according to the construction mode-
(i) without lining
(ii) with brick lining
(iii) of masonry rubble and
(iv) of terracotta rings.
The first-mentioned type should technically be regarded as the first human attempt to dig wells for water procurement purposes; but the earliest archaeological remains of dug wells are represented in India by brick-lined circular wells dating back to Harappa Culture as early as.
Ring wells have to be differentiated according to their construction from the wells of other styles. Well with circles, it was essentially a kind of well-built village for general use
The linings in terracotas are also known as terracotta rings in ring wells. Drilling, which is one of the old age methods used, is used for the extraction of potable water in rural areas.

Note:In the earlier times, the lining of wells with rubble masonry did not gain any popularity in India, except in the Bhir Mound Process at Taxila, for whatever reason (West Pakistan). Wells with lining of bricks or rings had a widespread distribution both in space and in time of the four styles mentioned above, and are still in vogue in different parts of India.