The transition to a circular economy with an emphasis on eco-innovation is just beginning both in Europe and in Romania, as a member country of the European Union. The whole economic system in which people operate must be circular, which means that it must eliminate conflicting aspects related to regulation, collaboration, governance, supply chain dynamics, and data transparency. However, the barriers to the transition to a circular economy are substantial, and it is up to states to work together to find innovative solutions to society’s problems. This article focuses on aspects related to eco-innovation in the field of drinking water quality in all administrative regions of Romania. In this regard, a study was undertaken, and the main objective pursued in was to identify and highlight the degree of eco-innovation of drinking water suppliers in seven underdeveloped regions of Romania. Starting from an analysis of the water management framework through the OECD Principles on Water Governance, it was possible to develop a study on drinking water supply companies in Romania. This study was performed based on specific indicators grouped by categories, and it aimed in two directions: on the one hand, the identification of drinking water distributors with a high degree of eco-innovation, which leads to quality certification of the drinking water supplied and which has the impact of encouraging household consumers to mainly use this type of supplied water to the detriment of PET bottled water (which has well-known major disadvantages in relation to environmental pollution and user health); on the other hand, the identification of drinking water supply companies with a low degree of eco-innovation, which is proof of the need for mandatory measures to improve drinking water quality, measures that can be taken at the supplier level but especially with support from the administrative and political environment.

This paper presents research conducted in the direction of analyzing the efficiency of filters used for drinking water intended for domestic consumption, with effects on the water quality gained from the public distribution network. A basic method that uses accessible techniques, such as optical microscopy and tests that involve the use of existing products on the consumer market, was developed regarding the filtration capacities of the main filters existing on the market—a method that has advantages, such as speed and ease of application, a unitary character in obtaining samples, low costs, and high efficiency. The technique approached is that of microscopy, and the samples used were taken from the laboratory tests made on the mentioned filters, using a specific experimental stand designed to support laboratory tests by using chosen filter cartridges. The research results obtained were analyzed to make a classification from the perspective of filtration efficiency, in terms of using statistical analysis tools (mathematical models and methods processed in MATLAB software). Moreover, by using a certain type of application based on specific mathematical algorithms, which takes into account some influential factors with a decisive role on household consumers, it was aimed to identify the optimal filter element for acquisition and use in its own regime. The aim of the study was to identify the optimal filter cartridge from the perspective of quality–price ratio.