Why were the British government pressured into making public health reforms during the 19th century?

It had nothing at all to do with the Labour Party (new or old), which did not even start to become a political force until a couple of generations later.

It did have a lot to do with successive cholera outbreaks, and in particular the pioneering work of Dr John Snow, who demonstrated that cholera was spread through contaminated water and not, as had previously been believed, bad smells.

If you go to Youtube and check out the poster called Extra Credits, you will find a very informative series of essays on John Snow.

You should also check out Joseph Bazalgette, who designed and built London's sewer system. Parliament was prompted into action on this in the wake of the "Great Stink" when a hot summer made the Thames (which had served as London's main sewer for centuries) unbearable to be close to, and caused parliament to shut down.

Check to see if your books have contents pages and/or appendices.

Wrong

maybe it was cos of the industrial revolution

Industry in the mid 19th century required a lot of labour.

If you were an employer having a sick labour force didnt do you any good

it may also have been that limited numbers of workers would have led to higher wages (supply and demand)

(after the black death in the 14th century there were very few people available to work, This led to large increases in wages for those who were still alive.
But then the landowners complained and laws were brought in to force wages back to pre-plague levels)

Since the "employers" had a virtual control over parliament they voted for measures that would ensure an ample supply of workers and therefore lower wages (more supply = lower costs, and lower costs = higher profits)

(cos in early 19th century only land/property owners could vote, and even when the voting laws were changed in mid 19th century the votes werent secret. So your employer could see who you voted for, and sack you if you didnt vote for who they told you to)

(what amazes me is why people think the victorian age (19th century) was "glorious"
It was- IF you were rich, if you werent you were f//ked by the rich)

The Labour Party wasn't founded until 1900,and even its predecessor Independent Labour Party not till 1893.

Cholera outbreaks and the repercussions of raw sewage being dumped in the Thames led to the public health reforms.

Watch 'The Sewer King' episode of 'Seven Wonders of the Industrial World' which gives excellent background details on Bazelgette's building of the London sewer system,and the reasons for its construction.

There was no labour party in the 19th century, the government was forced to reform the health of the nation when it started to affect parliament its self, like one summer in 1857 when they could not open the windows of the palace of Westminster because the river thames had turned into one giant sewer. There were several public health acts passed in the 19th century, in 1848, in 1872 and in 1875. The 1848 act created a central board of health, and dealt with things like street cleansing, water supply and sewers, they set up local boards around the country to enable councils to oversee these things,The public very much resented he boards, who raised the rates to improve the environment, the 1872 act required councils to appoint medical officers of health and inspectors of nuisances! The act of 1875 finally amended and consolidated the earlier acts and gave local sanitary authorities wider powers of enforcement in relation to drainage,sanitation ,and water supplies, for this purpose all councils were required to employ health inspectors ,and sanitary engineers, reformers however were disappointed that a central government health authority was not set up at this time,

The 'Great Stink' in 1858, By June the stench from the Thames become so bad that business in Parliament was affected, Iin the House of Commons, Members of Parliament were unable to use either the Committee Rooms or the Library because of the stench, This caused new sewers to be built.