get the water bill
The Spanish phrase 'llegar la factura del agua' translates to 'get the water bill' in English. This phrase is commonly used when a person receives their water utility bill. It is composed of 'llegar' (to get), 'la factura' (the bill) and 'del agua' (of water). So literarily it means 'to get the bill of water', but in proper English we'd say 'get the water bill'.
I don't even want to think about when the water bill arrives this month.
This sentence expresses the speaker's worry or reluctance to dealing with the upcoming water bill, possibly because it's expected to be high.
After the water bill comes, we will need to adjust our budget.
This sentence expresses a conditional future action which the speaker needs to take after receiving the water bill. It implies that the budget might need to be tightened or changed according to this bill.
I will make sure the water bill gets to you on time.
In this case, the speaker is reassuring the listener that they will make certain the water bill is delivered to them promptly, this might be in a context where the speaker is responsible for forwarding mail or bills.