Construction costs are currently skyrocketing

Here it was first increased to 1.50 per cubic meter, wastewater 2.20 but last time 9 years ago... I think that is okay

Not necessarily delayed. But with a separate invoice.
For us, these are also two different companies. Coincidentally, one comes as a notice, the other as an invoice. So they also have different legal forms.

Yes, one is a fee and therefore comes as a notice, and the other is simply a consumption invoice.
With us, the fee must always be paid at certain dates during the year (I think 4 or 5 dates) or it will be collected if a direct debit authorization has been given. The dates are published on the municipality’s homepage and in the newspaper (they might also generally be noted on the notice, I am not sure about that right now). The first one is now, for example, at the end of February.

Interesting, with us water and wastewater are managed by the water association in a single annual billing and both depend on the volume.

You all have cheap water. With us, the cubic meter of water costs €2.00 and wastewater €3.22. In addition, there are fees of €3.75 per month. With us, everything comes in one invoice from the city. The quarterly advance payment for our consumption is €176.00. The property tax will increase in 2025 according to the notice from €58.62 per quarter to €80.97.

6 people here - €73 / quarter. Bearable

We pay about 30ct/m3 in electricity costs for our own pump. No basic charge. Wastewater costs 80 €/year for sludge from the three-chamber septic tank.

The different billing methods arise from the fact that wastewater disposal is a sovereign task and is therefore usually carried out by an AöR, without VAT.
Water supply is then partially private, partially municipal utilities, where the AöR as a sister company handles the disposal. In the latter case, water and wastewater are usually invoiced simultaneously, otherwise separately.

High basic charges for water may not encourage saving but reflect reality. In fact, the fixed costs for laying and maintaining the network and waterworks are much higher than the small amount of electricity for the pumps per m3.
I once worked for a water supplier for several years. There was also consideration to do away with all the measuring and reading and calculation and just charge basic fees for the connections – at least for small consumers. It was actually more economical but politically not feasible.