Allah loves those who turn to Him constantly and He loves those who keep themselves pure and clean.
Prophet Muhammad (SAW) said, "Purify yourself because Islam is a religion of purity." Islam puts great emphasis on the purity and cleanliness of the body, and also on clothes, home, the environment and in all aspects of living.
After a microscopic investigation on those who regularly perform ablution and those who do not, science confirmed that the noses of those who perform ablution regularly remained clean, pure and empty from any microbes. Therefore, the nose and surrounding areas appeared clean and empty from any microbe. Whereas, those who do not perform ablution the nose is a harboring area for different types of harmful microbes such as cluster microbes, rosary microbes which spread quickly and organic microbes which cause many kinds of diseases.
Some cases of self poisoning result from the harmful microbes which stay in the nose. These microbes enter into the digestive system and the blood circulation and cause diseases. Therefore, Islam, asked Muslims to 'inhale' water into the nose three times during each ablution. As far as the rinsing-out the mouth is concerned it is proofed that it protects mouth and throats from inflammations, gingivitis and teeth decay and erosion by removing the remaining of food. It is medically confirmed that 90% of those who lose their teeth prematurely is because they don't clean their mouth & teeth regularly.