A New Habit for the Scorching Heat Era? "Summer Big Cleaning" Spreading Among Young People, About 20% of those in their 20s Participate

Ahead of "Summer Big Cleaning Day" on July 20th, established by "Claqua" (a home delivery water service), NAC Co., Ltd. (Head Office: Shinjuku-ku, Tokyo; President and CEO: Yuya Kawakami) conducted a "Survey on the Actual State of Home 'Summer Big Cleaning'" targeting 500 married men and women aged 20 to 60 nationwide.

The survey results revealed a high level of satisfaction, with approximately 75% of those who performed big cleaning in the summer responding that they "were glad they did it." On the other hand, the image of "big cleaning = year-end" remains strong, presenting a psychological hurdle to implementation. Amidst this, the increase in time spent at home (ienaka time) due to recent extreme heat and heightened awareness of hygiene against mold and bacteria may be boosting summer big cleaning.

Survey Overview

Survey Name: Survey on the Actual State of Home 'Summer Big Cleaning'

Survey Method: Internet Survey

Survey Period: June 19, 2026 - June 22, 2026

Target: 500 married men and women aged 20-60 nationwide

*In this survey, values are rounded to the second decimal place, so the total may not be 100%.

*When introducing the survey results, please cite "Survey by NAC Co., Ltd."

Background of Establishing "Summer Big Cleaning Day" and Claqua's Social Role

"Summer Big Cleaning Day" is an anniversary established by Claqua in July 2025, timed to coincide with the start of summer vacation for elementary and junior high schools, to encourage the habit of creating a hygienic and safe living environment not only in winter but also in summer.

While winter big cleaning is established as a year-end tradition, summer, with its high temperatures and humidity, is the season when mold and bacteria actively multiply. Hygiene management, especially in water-related areas, becomes an even more crucial point for maintaining a comfortable life. We hope this anniversary will serve as an opportunity to once again focus on these summer-specific hygiene challenges.

Survey Results

<1. What Comes to Mind When You Hear "Big Cleaning"> "Cleaning places not usually cleaned" is the most common answer. The perception of it being a year-end tradition is still strong.

The response "cleaning places not usually cleaned all at once" was the most frequent, indicating that big cleaning is recognized as an "event-like activity" separate from daily cleaning. At the same time, many responded with "year-end tradition," showing that the timing of big cleaning is still fixed. In other words, while big cleaning is widely understood, its "flexibility in timing" is still low.

<2. Frequency of Big Cleaning> 40% "Always do it every year." Big cleaning itself is established in daily life.

Big cleaning is performed in many households regardless of age, demonstrating that it is firmly rooted as a Japanese lifestyle habit. The frequency of "always do it every year" and "do it some years and not others" were the top responses, revealing that many people regularly perform big cleaning.

- About 30% of those in their 20s "always do it every year," while about 50% of those in their 60s do, showing a generational difference in frequency.

In their 20s, only 31.0% "always do it every year," whereas in their 60s, this figure reached 47.0%, indicating a tendency for big cleaning to be more established as a habit with increasing age. Many in younger generations responded that they "do it some years and not others," suggesting that while the awareness of big cleaning is shared, there are generational differences in implementation frequency.

<3. Image of Big Cleaning Timing> About 80% of the total have the image of "Big Cleaning = Year-End."

Regarding the image of "Big Cleaning = Year-End," 39.6% of the total responded "strongly have it," and 42.2% responded "somewhat have it," revealing that a total of 81.8% hold the perception that "big cleaning is something done at the end of the year."

- The weakening of the fixed idea "Big Cleaning = Year-End" is more pronounced among younger generations.

Looking at the age groups, the response "not at all" was 20.0% for those in their 20s, which is 16% higher than for those in their 60s. This indicates that younger generations tend to have more flexible values that are not bound by traditional habits. It is highly likely that the "timing of big cleaning" will diversify in the future due to the influence of these generations.

<4. Timing of Big Cleaning> About 1 in 5 people in their 20s perform "Summer Big Cleaning," a significant generational difference.

While winter was the timing for half of those in their 60s, and summer only 3.0% (a very small minority), 19.0% of those in their 20s performed big cleaning in the summer. This result indicates a significant difference in values and lifestyles regarding big cleaning between generations. Particularly among younger generations, it is thought that the timing is being dispersed due to the existence of dual-income households and a growing trend towards rational household management driven by increased time spent at home.

<5. Reasons for Not Doing Big Cleaning in Summer> The biggest hurdles to "Summer Big Cleaning" are "heat" and "lack of habit."

The top reason for not doing big cleaning in the summer was "it's hot and physically demanding," followed by "lack of habit." Regarding the first reason, when looking at age groups, 61.0% of those in their 60s and 28.9% of those in their 20s responded, reflecting the higher proportion among the 60s. Furthermore, as indicated by the results of Q3 and Q4, the lack of the concept or habit of "Summer Big Cleaning" itself appears to be a contributing factor.

<6. Reasons for Doing Big Cleaning in Summer> "Mold/Bacteria Countermeasures" account for about 40%, and "Longer time spent at home" accounts for about 30%, with a majority.

The main reasons for doing big cleaning in the summer seem to be related to the summer-specific living environment, such as "mold/bacteria countermeasures" and "longer time spent at home." Especially with the extreme heat in recent years, there is a stronger tendency to refrain from going out, and interest in comfort within the home is increasing. It is evident that changes in environmental factors such as temperature and working styles are increasing the need for "Summer Big Cleaning."

<7. Satisfaction with Summer Big Cleaning> About 80% of those who performed it were satisfied, realizing its value.

A total of 76.5% responded that they "strongly feel" or "somewhat feel" they were glad they did summer big cleaning, indicating a very high level of satisfaction. This suggests that the benefits realized exceed the perceived burden (such as the heat) before implementation.

<8. Areas to Clean in Summer> "Water-related areas" such as kitchens, bathrooms, and drains dominate the top rankings, reflecting high hygiene awareness.

Water-related areas such as kitchens, bathrooms, and drains ranked high. These are areas susceptible to the effects of humidity and temperature, posing higher risks specific to summer. This suggests that people performing summer big cleaning are more focused on "invisible dirt" and "hygiene management" rather than "visible dirt."

<9. Concerns During Summer Cleaning> Anxiety about "mold, bacteria, and odors" is evident.

"Mold growth," "proliferation of germs and bacteria," and "odors" were the top three concerns, clearly showing that many people are anxious about "invisible dirt" and "hygiene" in the summer, similar to the results of Q8. Compared to the results of Q1, where big cleaning is strongly perceived as "cleaning places not usually cleaned," it can be seen that summer has its own specific needs.

<10. Intention for Summer Big Cleaning> While opinions are divided, about 50% responded "would like to try incorporating it."

Opinions were divided on whether people would actually like to incorporate summer big cleaning. However, given the high satisfaction of those who have already done it, the main barrier for those who haven't is likely the unconscious psychological hurdle of "big cleaning is something done at the end of the year."

In Response to Survey Results

The results of this survey indicate that while the image of big cleaning = year-end is strong, about 20% of young people are performing "Summer Big Cleaning." The reasons for doing big cleaning in the summer are largely due to summer-specific living environments, such as "mold/bacteria countermeasures" and "longer time spent at home." It is evident that environmental changes, such as summer-specific dirt due to temperature and humidity, and increased time spent at home due to the heat, are increasing the need for "Summer Big Cleaning."

Furthermore, given the high satisfaction of those who have performed "Summer Big Cleaning," it is thought that many people find "mold/bacteria countermeasures" effective to some extent or are satisfied with it as a "rational timing" that aligns with environmental changes such as increased time spent at home. More than half of all age groups feel they "would like to try incorporating summer big cleaning," and it is presumed that the number of people doing big cleaning in the summer will continue to increase.

Beware of "Invisible Dirt" in Summer! What about the hygiene of your water server...?

Regular maintenance of water servers is also important

In summer, when mold and bacteria tend to proliferate, hygiene management of beverage equipment, not just water areas, is important. Water servers, in particular, are used daily, but internal cleaning is difficult, and "invisible dirt" can accumulate over time.

Claqua's "Server Whole! Ultra Sterilization*"

Claqua, a home delivery water service, has a maintenance system in place where the entire server unit is replaced once a year. At a maintenance center specializing in water server hygiene, each unit is disassembled, washed, and sterilized, and new spigots for cold and hot water, which are used daily, are replaced, maintaining internal cleanliness that is difficult to achieve at home.

*Refers to Claqua's (home delivery water) unique cleaning and sterilization maintenance method. This method has confirmed a 99.9% sterilization effect in internal company tests (June 2024, surveyed by our research institute).

Supplementary Materials

About NAC Co., Ltd. https://www.nacoo.com/

Since its founding in 1971 as a franchise member of Duskin Co., Ltd., our company has actively expanded its business domains centered on "convenience for living." Celebrating its 50th anniversary in 2021, in addition to the rental business with Duskin as its core, we are further growing by directly connecting with customers nationwide in a wide range of fields related to "living" and "housing," including the Claqua business that develops home delivery water services, the architectural consulting business that supports the management of local construction companies, the housing business, and the beauty and health business.

About Claqua https://www.crecla.jp/

Since the start of its business in 2002, Claqua has provided home delivery water services that align with people's lives, based on the philosophy of "safety and security." As a brand that handles "water," a vital infrastructure for life, we have established a quality control system to protect "quality that can be used with peace of mind for a long time, without change." This includes a direct delivery service through approximately 400 delivery bases nationwide, stable water quality management through plants across the country, and unique maintenance centers specializing in water server hygiene. Claqua aims to be "a water server that is trusted and used for the next 100 years." We will continue to fulfill our responsibility as a service that supports and protects the everyday aspects of life.

NAC Co., Ltd. Company Profile

Company Name: NAC Co., Ltd. Year Established: May 20, 1971 Capital: 6,729,493,750 yen Representative: Yuya Kawakami Number of Employees: 1,699 (Consolidated, as of the end of March 2026) Head Office Location: Shinjuku Center Building 42F, 1-25-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Phone Number: 03-3346-2111 (Representative)