Building Sustainable Water Infrastructure Tailored to Local Needs
At our company, we specialize in installing small-scale water supply systems designed to suit the unique characteristics of each community.
In this article, we introduce a case study from 2022–2023, where our director led a water system renovation project in Futtsu City, Chiba Prefecture.
Project Overview
📍 Location: Futtsu City, Chiba Prefecture
📅 Installation Period: December 2022 – March 2023
💧 Start of Water Supply: April 2023
Overview of the Water Supply System
🏗️ Water Treatment Process
- Upflow gravel filtration
- ozone oxidation
- biological filtration
- MF membrane filtration
- UV sterilization
- chlorine disinfection
👥 Target Population: 29 people (as planned)
Background
This rural area relied on mountain stream water and a simplified supply system with a mechanical slow sand filtration unit. Over time, the aging infrastructure began producing discolored tap water.
After the record-breaking rainfall in October 2019, the source flow decreased and turbidity worsened during rainy periods. Meanwhile, population decline and the aging of local residents made the management of the facility increasingly burdensome.
To address these issues, a renewal of the water facility was implemented as a fiscal 2022 project.
Key Features of the New Facility
Upflow Gravel Filtration System
Previously, the intake included a gravel filter that required residents to clean it twice a year—an arduous task.
This was replaced with an upflow gravel filtration unit that eliminated the need for manual cleaning and efficiently removed sediments from the raw water, reducing strain on the main purification system.
MF (Microfiltration) Membrane System
To combat turbidity and discoloration, a low-maintenance MF membrane system was introduced.
This system effectively removes both suspended solids and humic substances (the source of discoloration).
With routine flushing and periodic chemical cleaning, the membrane has not required replacement in over three years, ensuring cost-effective operation.
Ozone Oxidation Unit
While MF membranes can remove humic substances, high discoloration levels during certain seasons posed a risk of increased membrane maintenance.
To ease this burden, an ozone oxidation system was added to break down these color-causing compounds.
The byproducts are further processed in the subsequent biological filtration stage.
Biological Filtration Unit
This unit helps remove dissolved organic compounds, degradation byproducts, nutrients, and suspended particles.
It enhances the taste of the tap water and reduces the frequency of chemical membrane cleaning.
Automated Chlorine Control System
Previously, chlorine dosing was manually adjusted using a pump dial, based on seasonal intuition.
This sometimes led to over- or under-chlorination, adding to the management workload.
The new system automatically adjusts chlorine levels to a preset concentration in the reservoir, significantly reducing operator burden.
Looking Ahead
This project demonstrates a successful approach to reducing the management burden of rural water systems while maintaining safe and high-quality supply—an increasingly urgent issue as population decline spreads across Japan.
We are committed to promoting the adoption of sustainable small-scale water systems nationwide, responding flexibly to the unique water challenges of each region.
If you are interested in learning more about this system or considering a similar installation, please feel free to contact us.