The second pipe could deliver 12 million gallons a day, giving a total capacity of the aqueduct of twenty million gallons a day.
The water level was raised to 35 ft above natural; the area of the lake now increasing to 690 acres.
Seventy-nine acres of Shoulthwaite Moss (north of Thirlmere) were reclaimed as winter pasture to compensate for the loss of acreage around Thirlmere.
A third pipe was authorised in 1906,
construction began in October 1908, and was completed in 1915: this increased the potential supply from Thirlmere to thirty million gallons a day against an average daily demand which had now reached forty-five million gallons: in the summer of 1911 it had again been necessary to suspend the water supply at night.
 The lake was then raised to fifty feet above natural; a fourth and final pipeline was completed in 1927, its authorisation having been delayed by the First World War until 1921; as early as 1918 Manchester Corporation had identified the need for a further source of water, and identified Haweswater as that source.
At the committee stage of Manchester's 1919 Bill to tap Haweswater, the average daily demand on Manchester's water supply in 1917 was said to have been 51.2 million gallons a day, with the reliable supply from Longdendale being no more than 20 million gallons a day and Thirlmere being able to supply 30 million gallons a day, which would rise to 40 million gallons a day when the fourth pipe was laid.
The aqueduct capacity could be increased to fifty million gallons a day by laying a fifth pipe, but could not be increased beyond that whilst the aqueduct was still being used to deliver water to Manchester.

At the committee stage of the Haweswater bill, objectors made no mention of the aesthetic concerns raised against the Thirlmere bills: "The world now knows that many of the fears then expressed were very foolish ones, and would never be realised under any circumstances, or at any place" said the Yorkshire Post although Manchester countered the suggestion that it should not annex Haweswater, but instead further raise the level of Thirlmere because "it would mean such injury to the Lake District that they would have the whole country up against them"
When the Lords defeated Manchester's Bill for abstraction of water from Ullswater in 1962, however, many speakers pointed to Manchester's stewardship of Thirlmere to show why the Bill should be defeated:
to improve the retention of water in the catchment area, from 1907 onwards Manchester had planted extensive stands of conifers on both banks of the reservoir; as they grew, they had radically altered the appearance of the area, and (as James Lowther - now Lord Ullswater - complained) destroyed the views from the road on the west bank provided to give the public views of Helvellyn
As Thirlmere water became more essential as a supply to Manchester, the draw-down of the reservoir in dry weather increased to double the 8–9 foot promised in the 1870s.

"Large flooding of a valley bottom means an end to farming, and Thirlmere and Mardale are farmless and depopulated" but this was not just because of the higher water level.
There was no provision for water treatment downstream of Thirlmere (or Longdendale), and Manchester therefore relied on minimising pollution at source.
To achieve this, it minimised human activity in the catchment area.
Much of the settlement around Wythburn church (including the Nag's Head, a coaching inn with Wordsworthian associations) remained above water level but it was suppressed, accommodation for necessary waterworks employees being provided at Fisher End and Stanah east of the northern end of the reservoir.
Eventually Manchester Corporation closed Wythburn churchyard, St John's in the Vale being now more convenient for its future customers.

To protect the water from contamination by tourists and visitors, bathing boating and fishing were prohibited, and access to the lake effectively banned.
This policy was supported by "...barbed wire, wire netting, regimented rows of conifers and trespass warning notices, as common as 'Verbot
The second pipe could deliver 12 million gallons a day, giving a total capacity of the aqueduct of twenty million gallons a day. The water level was raised to 35 ft above natural; the area of the lake now increasing to 690 acres. Seventy-nine acres of Shoulthwaite Moss (north of Thirlmere) were reclaimed as winter pasture to compensate for the loss of acreage around Thirlmere. A third pipe was authorised in 1906,
construction began in October 1908, and was completed in 1915: this increased the potential supply from Thirlmere to thirty million gallons a day against an average daily demand which had now reached forty-five million gallons: in the summer of 1911 it had again been necessary to suspend the water supply at night.  The lake was then raised to fifty feet above natural; a fourth and final pipeline was completed in 1927, its authorisation having been delayed by the First World War until 1921; as early as 1918 Manchester Corporation had identified the need for a further source of water, and identified Haweswater as that source. At the committee stage of Manchester's 1919 Bill to tap Haweswater, the average daily demand on Manchester's water supply in 1917 was said to have been 51.2 million gallons a day, with the reliable supply from Longdendale being no more than 20 million gallons a day and Thirlmere being able to supply 30 million gallons a day, which would rise to 40 million gallons a day when the fourth pipe was laid. The aqueduct capacity could be increased to fifty million gallons a day by laying a fifth pipe, but could not be increased beyond that whilst the aqueduct was still being used to deliver water to Manchester.
At the committee stage of the Haweswater bill, objectors made no mention of the aesthetic concerns raised against the Thirlmere bills: "The world now knows that many of the fears then expressed were very foolish ones, and would never be realised under any circumstances, or at any place" said the Yorkshire Post although Manchester countered the suggestion that it should not annex Haweswater, but instead further raise the level of Thirlmere because "it would mean such injury to the Lake District that they would have the whole country up against them"
When the Lords defeated Manchester's Bill for abstraction of water from Ullswater in 1962, however, many speakers pointed to Manchester's stewardship of Thirlmere to show why the Bill should be defeated:
to improve the retention of water in the catchment area, from 1907 onwards Manchester had planted extensive stands of conifers on both banks of the reservoir; as they grew, they had radically altered the appearance of the area, and (as James Lowther - now Lord Ullswater - complained) destroyed the views from the road on the west bank provided to give the public views of Helvellyn
As Thirlmere water became more essential as a supply to Manchester, the draw-down of the reservoir in dry weather increased to double the 8–9 foot promised in the 1870s.
"Large flooding of a valley bottom means an end to farming, and Thirlmere and Mardale are farmless and depopulated" but this was not just because of the higher water level. There was no provision for water treatment downstream of Thirlmere (or Longdendale), and Manchester therefore relied on minimising pollution at source. To achieve this, it minimised human activity in the catchment area. Much of the settlement around Wythburn church (including the Nag's Head, a coaching inn with Wordsworthian associations) remained above water level but it was suppressed, accommodation for necessary waterworks employees being provided at Fisher End and Stanah east of the northern end of the reservoir. Eventually Manchester Corporation closed Wythburn churchyard, St John's in the Vale being now more convenient for its future customers.
To protect the water from contamination by tourists and visitors, bathing boating and fishing were prohibited, and access to the lake effectively banned. This policy was supported by "...barbed wire, wire netting, regimented rows of conifers and trespass warning notices, as common as 'Verbot
Thirlmere