Different concentration indexes are calculated for the Dutch waste collection market and all show that this market was highly concentrated in 2002, 2006, 2010 and 2014. The estimation results in 2002 show that private collection is cheaper but high concentration increases costs of private collection and therefore (partly) offsets the advantage of contracting out. In 2006, the savings gained from privatisation and also the effect of concentration disappear, probably due to the introduction of a VAT-compensation fund. In 2010, for an area with a radius of 30 km, high concentration increases costs, but for larger areas, this effect mostly disappears. For 2014, in most estimations, this concentration effect disappears. If we include fixed effects for a panel, the cost advantage of inter-municipal cooperation is larger than that of private production and concentration effects also disappear. Overall, these estimation results are rather independent of the concentration indexes used, if we investigate several indexes as an alternative for the Herfindahl–Hirschman index.