In the Medieval period there was no concept of public health. The powerful did wash contrary to popular belief and did their best to avoid filth and bad smells. Castles of the period were all careful to have an external outlet for toilet waste to avoid illness in a siege when otherwise waste might collect within a castle.
Monasteries were hugely significant in treating the sick. Often in exposed, open countryside and set alongside a river or water supply they were healthy places. They treated ordinary locals in their hospitals. Monks and nuns were very clean and bathed often. Food hygiene was also carefully observed. Most abbeys and monasteries have toilets (like the infirmary) built away from the main living area, toilets are usually sited over the river at the downstream end of the Abbey complex, as at Fountains Abbey.
The Peasants and villeins in the rural areas tended to be healthier. Working in the fresh air and with access to clean water, they bathed in streams and rivers.
Those poor in the towns had more hazards to contend with. Clean water and sewerage were difficult to find. Food (meat in particular) was often bad. Butchers were routinely fined for creating mess and filth. The Government saw this as a local issue for individuals to solve. Toilets in London were built over the Thames, private houses used pots emptied into the streets or privies with a cesspool.
Some councils did try to act, however they lacked organisation and direction. London had rakiers whose job was to empty cesspools. There were some laws against creating mess and filth in the streets.