What running costs come with a collection pit?

You pay per collection, not a flat monthly fee. How often the tanker has to come depends on the size of the pit and on how many people live in the house year round. A holiday home used for two weeks a year is in a different league from a household of four all year. Prices differ between the regional utility and private operators and depend on the distance travelled. There is no single national tariff, which is why no figure is quoted here. Keep the receipts: the municipality may ask for proof of proper disposal.