1. The Effects Of Drain Cleaner on Microbes
Matt Zagrocki
Central Catholic High School
Grade 9

2. Problem
What effect does drain cleaner have on the survivorship of Escherichia coli?

3. Purpose
This experiment was conducted to see the effect drain cleaner has on E. coli.
Will it decrease survivorship?
Does concentration have an effect?
Are eco friendly drain cleaners less damaging?

4. Application to the Real World
Drain cleaners are commonly used by the American household
Substances poured down drains can leak into the watershed
E. coli was used to model fresh water prokaryotes
Can a drain cleaner effectively sterilize household sinks and drains?

5. Drano Max Gel (industrial)
Widely used
Main ingredient is Sodium Hydroxide, a caustic
Other ingredients include sodium hypochlorite, (bleach) water, sodium silicate (corrosion inhibitor) and a surfactant blend (cleaning agent)
pH of 11

6. Sodium Hydroxide Molecular formula NaOH
Highly reactive with other metals
Corrosive to living matter
Also referred to as lye
Synthetically manufactured

7. Green Gobbler (eco friendly)
Claimed to be biodegradable and eco-friendly
EPA approved
Unnamed hydroxide identified as “trade secret/proprietary”
Ph of 13
Other ingredients are water, xanthan gum, alcohol ethoxylate, modified magnesium silicate

8. Escherichia coli Common bacteria found in intestinal tract of animals
Works its way into water through feces
Gram Negative
Ubiquitous
classified as a facultative anaerobe
Thrives in pH neutral environment
Survives in pH range

9. Hypothesis
Null Hypothesis – The drain cleaners will have no effect on E. Coli
Alternate Hypothesis – The drain cleaners will significantly reduce survivorship of E. coli
Green Gobbler will have less negative effects on E. coli survivorship than Drano

10. Materials
LB Agar Plates (0.5% yeast extract, 1% tryptone, 1% sodium chloride)
Pipettes (p. 20, 200, and 1000)
%70 Ethanol (to sterilize)
E. coli
Permanent Marker
Drano Max Gel Drain Cleaner
Vortex
Green Gobbler Eco-Friendly Drain Cleaner
Test Tubes (sterile)
Test tube racks
Sterile Dilution Fluid (10mm KH2PO4, 1 mm MgSO4, .1mm CaCl2, 100 mm NaCl)
Spreader Bars

11. Procedures 1. E. coli was grown overnight in sterile LB media.
2. Samples of the overnight cultures were added to fresh media in sterile sidearm flasks.
3. The cultures were placed in an incubator (37°C) until a density of 50 Klett spectrophotometer units was reached. This represents a cell density of approximately 108 cells/mL.
4. The cultures were diluted in sterile dilution fluid to a concentration of approximately 105 cells/mL.

12. Procedures (continued)
5. Six test tubes were set up as follows:
10% 1%
0.1%
0.01%
0.001% 0%
E. Coli 1
mL of drain cleaner
0.1
0.01
Substock
mL of sterile dilution fluid 8
8.9
8.99 9
Total volume 10

13. pH values of Concentrations
Stock
10% 1%
.01%
.001%
Drano 11
≈8.1
≈7.1 ≈7
Green Gobbler 13
≈8.3
≈7.3

14. Procedures (continued)
6. The tubes were vortexed and allowed to sit in room temperature for 10 minutes mL aliquots were pipetted onto agar plates 8. The plates were placed in an incubator for 24 hours, and then the colonies were counted visually. Each colony was assumed to have arisen from one cell.

15. E. Coli Survivorship in different concentrations of Drano
P = 3.5E-26

16. Dunnett’s Test- Drano T crit – 3.39 P value < 0.05 Concentration
T Value
Result
0.001%
Significant
0.01%
0.1% 1%
10%
T crit – 3.39

17. E. Coli Survivorship in different concentrations of Green Gobbler
P = 4.7E-27

18. Dunnett’s Test – Green Gobbler
P value < 0.05
Concentration
T Value
Result
0.001%
Significant
0.01%
0.1% 1%
10%
T crit – 3.39

19. P = 3.5E-26
P = 4.7E-27
P < 0.05
P < 0.05
P < 0.05

20. Conclusions Null Hypothesis was rejected
All concentrations with both drain cleaners had a significant effect
Drano appeared to have a greater negative impact at lower concentrations
Higher concentrations killed more colonies

21. Limitations Only one bacteria was used
Only 5 concentrations were tested
Only two types of drain cleaner were tested
Plating, vortexing, pipetting, and exposure times could have been slightly unsynchronized
Study does not reveal other effects on bacterial health

22. Extensions Use different types of bacteria
Use more types of drain cleaner
Use different exposure times
Additional trials per group

23. Sources
“DISSOLVE Drain Opener - Liquid Hair&Grease Clog Remover (32 oz.).” Green Gobbler, greengobbler.com/products/dissolve-liquid-hair-grease-clog- remover?variant=
“Max Gel Clog Remover.” Drano® | SC Johnson, us/products/drano-max-gel-clog-remover.
“SODIUM HYDROXIDE.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, pubchem.ncbi.nlm.nih.gov/compound/sodium_hydroxide.
“E.coli (Escherichia coli).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 25 Jan. 2018,

24. Anovas Anova- Single Factor / Drano SUMMARY Groups Count Sum Average
Variance x 6
.1x
.01x
.001x
274
.0001x
941
0x (control)
2597
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 5
3.4886E-26
Within Groups
13873 30
Total 35
Anova: Single Factor / Green Gobbler
SUMMARY
Groups
Count
Sum
Average
Variance x 6
.1x
.01x
179
.001x
940
.0001x
1967
0x (control)
2597
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 5
4.7456E-27
Within Groups 30
Total 35