I believe the car in the first photo is 06207, one of at least 3 of the 6200 series flats that were converted to water service cars, the others were 06213 and 06217 (short dome that Fritz refers to). Search the forum for their numbers or the phrase 'water service' or 'water car'. Old tenders were often converted as well.
The Friend's Dorman collection has quite a few shots of water cars here:
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www.cumbrestoltec.org]
Narrow Gauge Pictorial Vol. 10, Numbered Work Cars of the D&RGW is also a great resource, though out of print and hard to find but well worth it.
Mike