In message ,
TWStannard writes
Anyone have any experience of this type of pond? How does one go about the
'puddling' and how durable are they? Contemplating building a water
feature, and as I live on solid clay, it could save me a tonne of money and
lifting! )

This may be of some help - I first posted this to a similar question a
few years ago.

Here is an extract from The Book of the Garden Pond by George Hervey &
Jack Hems, published by Stanley Paul in 1958.

"The introduction of cement has enabled the gardener to build a pond at
no great expense, with the minimum of hard work and with a guarantee of
its durability. Once, however, the gardener was compelled to make a pond
of clay or go without. Today ponds of puddled clay are rarely seen,
except in districts where clay predominates in the local soil. A clay
pond has the virtue of being more in keeping with a natural pond, but
that is about its only virtue. It calls for considerable skill if it is
to be made watertight (and that surely a pond must be), and for so much
hard work that posterity would hardly have raised a surprised eyebrow if
Eurystheus had included one among the tasks that he set Hercules.

A hole is dug to the required size ('Easy the way down to hell'). The
clay, which must be free from stones and the like, is collected ('But to
retrace your steps'), soaked and puddled to the consistency of
plasticine. The puddling must be done thoroughly if the pond is to be
watertight ('To regain the upper air') and straw may be worked into the
clay, to act as a binding agent, although it is not absolutely
necessary. When the clay has been thoroughly puddled ('There lies the
task, there lies the toil') the excavation is lined with crushed clinker
and small stones, and a layer of soot, about three inches thick, to
discourage worms. The clay is laid over it to a depth of at least eight
inches. it is rammed down until the surface is almost dry, perfectly
smooth and free from air-holes. The walls of the pond should be built in
the same way, not however, vertically, but sloping slightly outwards to
lessen the risk of their caving in. The pond should be rinsed and filled
before the clay is allowed to dry, and must be kept filled at all times,
because once the clay dries it cracks.
Puddled clay is suitable only for a small pond, and even so, is not
always to be trusted. Clay ponds are very liable to spring leaks,
particularly when roots of the water plants penetrate the clay, or worms
tunnel into it, soot not withstanding".

--
Robert