That discussion may well have been my instigation too lol. I have done research on it and spoken with both Norman and Barrie but still looking for that elusive photo (other than the arial shot). Here's a little mention of it from the Shields Daily Gazette and Shipping Telegraph in February 1882 (Sunderland and South Shields Water Company):-

Your directors have to report that income to the company continues to increase, but, owing to the extensions made at Dalton and Hebburn Fell, in anticipation of prospective demand for water (not yet realized consequence principally of the depression in the chemical trade),

The completion of the covered reservoir Hebburn Fell enables the company to store largely increased quantity of water, thus affording an additional guarantee that tha supply to that large, and important district wiil be fully maintained.

The reservoir at Hebburn, which cost £19,515 7s 7d, was also entirely paid for. The result the expenditure upon the Dalton works and the Hebburn reservoir was that they had pumped eighteen hundred millions of gallons water, which about 130,000,000 gallons more than in the previous year. He contrasted the waste last winter, owing to the continued frost, with the waste this winter, which was almost nil, owing to the absence of frost. There was a decrease in the consumption of water on Tyneside, owing to the depression in the chemical trade, but, on the other hand, there was steady increase in Sunderland, both for trade and domestic purposes. This increase was a little over £1,200, and the decrease on Tyneside was nearly £1,000. Shields the increase for domestic purposes was £414. He had seen by the newspapers that there was great demand for houses at Jarrow,. and the building there would tend|to inciease the number of their customers.