Everyone, including prisoners, has a right to human dignity. The purpose of imprisonment is intended to be rehabilitation and the only punishment is deprivation of liberty, not neglect, violence and ill health. These conditions do not assist in rehabilitation, and ultimately will not prevent crime.
Remand prisoners specifically are awaiting trial and are technically still innocent. Not only are they imprisoned without being convicted, some for as long as 8 years, but they are forced to live in terrible conditions.
The treatment of remand detainees and inmates also has an impact on the communities they ultimately return to. Studies have shown that in order to prevent transmission of TB in the general population, you need to beat it in prisons. Similarly, the norms that contribute to gender based violence learned or entrenched in prison return to the community with the detainees upon their release. Prisons and their inmates actually affect all of us, directly or indirectly.