One might think that the UNHCR should have experts on hand who have ready made designs for sewage, water and electricity in refugee camps, but then one looks at the horrors of Moria and the other "camps" in Greece. It is utterly shameful that people in need depend on volunteers taking care of such basic needs. Thanks, OP.
There, they absorb as many taxpayer resources as possible, and work menial cash jobs - sending the proceeds back to their homelands to repay the initial 'investment'.
Its basically a huge scam, an unholy alliance between European elites who want cheap labour and European leftists who want to virtue signal. The average European citizen loses out hugely from the undermining of the labour market, the increase in crime, the destruction of national culture and identity, and the lack of investment into European automation and robotics (since illegal labour is so cheap instead).
This is where these migrants in Greece will end up: https://www.dw.com/en/spains-sea-of-plastic-where-europe-get...
It would be simpler to assume direct control over parts of Africa and farm produce there, as well as providing Universal access for local women to education, contraception and abortion. This would encourage actual long-term development of the region and tackle overpopulation (the root cause of these migration outflows).