Agents selling a 23,000-acre estate in Powys have asked potential buyers for more information before putting their bids before the owners Severn Trent.
The details about the Lake Vyrnwy estate could go before the utility company's board in either December or January, said Knight Frank.
The tendering process ended in September, and it is understood there were a number of inquiries.
Knight Frank said it wanted to ensure each offer was judged fairly.
The beauty spot, which features a conservation area, nature reserve, sites of special scientific interest and several farms in north Powys, has been split into four lots and is valued at £11m.
Among those who have bid for the rural estate is businessman Rhys Jones.
Mr Jones, 41, who lives in Poland but is from Bala in Gwynedd, is chief executive of Celtic Property Development, which has assets of 200m Euros (£170m).
RSPB Cymru and Mid Wales Housing Association have submitted a joint bid for the estate.
A Knight Frank spokesman said: "The sale has not been delayed at all, but we are making sure that each offer is judged on a level playing field and against the same criteria.
"For this reason we have asked for further information from the bidders to ensure that the successful bidder(s) are put forward to Severn Trent's board.
"Given the process of signing off the sale, a decision will not be made until January 2011 from the Severn Trent board and (watchdog) OFWAT.
"There is obviously also the three-month consultation period with CCW (Countryside Council for Wales) and this will be ongoing through the process to safeguard the Site of Special Scientific Interest."
The land on the estate has been split into four lots and includes 31 properties, but concerns have been raised about what the sale would mean for its tenants.
The Liverpool Corporation built Lake Vyrnwy, a reservoir, in the late 19th Century to supply water to the city.
The land around the lake is being sold on a 125-year lease.